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#include <bits/stdc++.h>
using namespace std;

namespace atcoder {

namespace internal {

#if __cplusplus >= 202002L

using std::bit_ceil;

#else

// @return same with std::bit::bit_ceil
unsigned int bit_ceil(unsigned int n) {
    unsigned int x = 1;
    while (x < (unsigned int)(n)) x *= 2;
    return x;
}

#endif

// @param n `1 <= n`
// @return same with std::bit::countr_zero
int countr_zero(unsigned int n) {
#ifdef _MSC_VER
    unsigned long index;
    _BitScanForward(&index, n);
    return index;
#else
    return __builtin_ctz(n);
#endif
}

// @param n `1 <= n`
// @return same with std::bit::countr_zero
constexpr int countr_zero_constexpr(unsigned int n) {
    int x = 0;
    while (!(n & (1 << x))) x++;
    return x;
}

}  // namespace internal

}  // namespace atcoder

namespace atcoder {

#if __cplusplus >= 201703L

template <class S, auto op, auto e> struct segtree {
    static_assert(std::is_convertible_v<decltype(op), std::function<S(S, S)>>,
                  "op must work as S(S, S)");
    static_assert(std::is_convertible_v<decltype(e), std::function<S()>>,
                  "e must work as S()");

#else

template <class S, S (*op)(S, S), S (*e)()> struct segtree {

#endif

  public:
    segtree() : segtree(0) {}
    explicit segtree(int n) : segtree(std::vector<S>(n, e())) {}
    explicit segtree(const std::vector<S>& v) : _n(int(v.size())) {
        size = (int)internal::bit_ceil((unsigned int)(_n));
        log = internal::countr_zero((unsigned int)size);
        d = std::vector<S>(2 * size, e());
        for (int i = 0; i < _n; i++) d[size + i] = v[i];
        for (int i = size - 1; i >= 1; i--) {
            update(i);
        }
    }

    void set(int p, S x) {
        assert(0 <= p && p < _n);
        p += size;
        d[p] = x;
        for (int i = 1; i <= log; i++) update(p >> i);
    }

    S get(int p) const {
        assert(0 <= p && p < _n);
        return d[p + size];
    }

    S prod(int l, int r) const {
        assert(0 <= l && l <= r && r <= _n);
        S sml = e(), smr = e();
        l += size;
        r += size;

        while (l < r) {
            if (l & 1) sml = op(sml, d[l++]);
            if (r & 1) smr = op(d[--r], smr);
            l >>= 1;
            r >>= 1;
        }
        return op(sml, smr);
    }

    S all_prod() const { return d[1]; }

    template <bool (*f)(S)> int max_right(int l) const {
        return max_right(l, [](S x) { return f(x); });
    }
    template <class F> int max_right(int l, F f) const {
        assert(0 <= l && l <= _n);
        assert(f(e()));
        if (l == _n) return _n;
        l += size;
        S sm = e();
        do {
            while (l % 2 == 0) l >>= 1;
            if (!f(op(sm, d[l]))) {
                while (l < size) {
                    l = (2 * l);
                    if (f(op(sm, d[l]))) {
                        sm = op(sm, d[l]);
                        l++;
                    }
                }
                return l - size;
            }
            sm = op(sm, d[l]);
            l++;
        } while ((l & -l) != l);
        return _n;
    }

    template <bool (*f)(S)> int min_left(int r) const {
        return min_left(r, [](S x) { return f(x); });
    }
    template <class F> int min_left(int r, F f) const {
        assert(0 <= r && r <= _n);
        assert(f(e()));
        if (r == 0) return 0;
        r += size;
        S sm = e();
        do {
            r--;
            while (r > 1 && (r % 2)) r >>= 1;
            if (!f(op(d[r], sm))) {
                while (r < size) {
                    r = (2 * r + 1);
                    if (f(op(d[r], sm))) {
                        sm = op(d[r], sm);
                        r--;
                    }
                }
                return r + 1 - size;
            }
            sm = op(d[r], sm);
        } while ((r & -r) != r);
        return 0;
    }

  private:
    int _n, size, log;
    std::vector<S> d;

    void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
};

}  // namespace atcoder



template <typename T> T mod_inv_in_range(T a, T m) {
	// assert(0 <= a && a < m);
	T x = a, y = m;
	// coeff of a in x and y
	T vx = 1, vy = 0;
	while (x) {
		T k = y / x;
		y %= x;
		vy -= k * vx;
		std::swap(x, y);
		std::swap(vx, vy);
	}
	assert(y == 1);
	return vy < 0 ? m + vy : vy;
}

template <typename T> struct extended_gcd_result {
	T gcd;
	T coeff_a, coeff_b;
};
template <typename T> extended_gcd_result<T> extended_gcd(T a, T b) {
	T x = a, y = b;
	// coeff of a and b in x and y
	T ax = 1, ay = 0;
	T bx = 0, by = 1;
	while (x) {
		T k = y / x;
		y %= x;
		ay -= k * ax;
		by -= k * bx;
		std::swap(x, y);
		std::swap(ax, ay);
		std::swap(bx, by);
	}
	return {y, ay, by};
}

template <typename T> T mod_inv(T a, T m) {
	a %= m;
	a = a < 0 ? a + m : a;
	return mod_inv_in_range(a, m);
}

template <int MOD_> struct modnum {
	static constexpr int MOD = MOD_;
	static_assert(MOD_ > 0, "MOD must be positive");

private:
	int v;

public:

	modnum() : v(0) {}
	modnum(int64_t v_) : v(int(v_ % MOD)) { if (v < 0) v += MOD; }
	explicit operator int() const { return v; }
	friend std::ostream& operator << (std::ostream& out, const modnum& n) { return out << int(n); }
	friend std::istream& operator >> (std::istream& in, modnum& n) { int64_t v_; in >> v_; n = modnum(v_); return in; }

	friend bool operator == (const modnum& a, const modnum& b) { return a.v == b.v; }
	friend bool operator != (const modnum& a, const modnum& b) { return a.v != b.v; }

	modnum inv() const {
		modnum res;
		res.v = mod_inv_in_range(v, MOD);
		return res;
	}
	friend modnum inv(const modnum& m) { return m.inv(); }
	modnum neg() const {
		modnum res;
		res.v = v ? MOD-v : 0;
		return res;
	}
	friend modnum neg(const modnum& m) { return m.neg(); }

	modnum operator- () const {
		return neg();
	}
	modnum operator+ () const {
		return modnum(*this);
	}

	modnum& operator ++ () {
		v ++;
		if (v == MOD) v = 0;
		return *this;
	}
	modnum& operator -- () {
		if (v == 0) v = MOD;
		v --;
		return *this;
	}
	modnum& operator += (const modnum& o) {
		v -= MOD-o.v;
		v = (v < 0) ? v + MOD : v;
		return *this;
	}
	modnum& operator -= (const modnum& o) {
		v -= o.v;
		v = (v < 0) ? v + MOD : v;
		return *this;
	}
	modnum& operator *= (const modnum& o) {
		v = int(int64_t(v) * int64_t(o.v) % MOD);
		return *this;
	}
	modnum& operator /= (const modnum& o) {
		return *this *= o.inv();
	}

	friend modnum operator ++ (modnum& a, int) { modnum r = a; ++a; return r; }
	friend modnum operator -- (modnum& a, int) { modnum r = a; --a; return r; }
	friend modnum operator + (const modnum& a, const modnum& b) { return modnum(a) += b; }
	friend modnum operator - (const modnum& a, const modnum& b) { return modnum(a) -= b; }
	friend modnum operator * (const modnum& a, const modnum& b) { return modnum(a) *= b; }
	friend modnum operator / (const modnum& a, const modnum& b) { return modnum(a) /= b; }
};

template <typename T> T pow(T a, long long b) {
	assert(b >= 0);
	T r = 1; while (b) { if (b & 1) r *= a; b >>= 1; a *= a; } return r;
}

using num = modnum<998244353>;

template<int L> using mat = array<array<num, L>, L>;

template<int L> mat<L> mul(mat<L> a, mat<L> b){
    mat<L> c;
    for(int i = 0; i < L; i++) for(int j = 0; j < L; j++) c[i][j] = 0;
    for(int i = 0; i < L; i++){
        for(int j = 0; j < L; j++){
            for(int k = 0; k < L; k++){
                c[i][k] += a[i][j] * b[j][k];
            }
        }
    }
    return c;
}

template<int A2> mat<A2> op(mat<A2> a, mat<A2> b){
    return mul<A2>(a, b);
}

template<int A2> mat<A2> e(){
    mat<A2> r;
    for(int i = 0; i < A2; i++) for(int j = 0; j < A2; j++) r[i][j] = int(i == j);
    return r;
}

template<int A> struct info {
    int all_msk; // always one way to use no
    array<int, A> pref_mask;
    array<int, A> suff_mask;
    array<array<num, A>, A> ways;
};

template<int A> info<A> combine(info<A> a, info<A> b){
    info<A> res;
    for(int i = 0; i < A; i++) res.pref_mask[i] = 0;
    for(int i = 0; i < A; i++) res.suff_mask[i] = 0;
    for(int i = 0; i < A; i++) for(int j = 0; j < A; j++) res.ways[i][j] = 0;
    res.all_msk = a.all_msk | b.all_msk;
    for(int x = 0; x < A; x++){
        if(a.all_msk & (1 << x)){
            res.pref_mask[x] = a.pref_mask[x];
        } else {
            res.pref_mask[x] = a.all_msk | b.pref_mask[x];
            for(int y = 0; y < A; y++){
               res.ways[x][y] += b.ways[x][y];
            }
        }
        if(b.all_msk & (1 << x)){
            res.suff_mask[x] = b.suff_mask[x];
        } else {
            res.suff_mask[x] = b.all_msk | a.suff_mask[x];
            for(int y = 0; y < A; y++){
                res.ways[y][x] += a.ways[y][x];
            }
        }
    }
    for(int x = 0; x < A; x++){
        for(int y = 0; y < A; y++){
            if(a.suff_mask[x] & (1 << y)) continue;
            if(b.pref_mask[y] & (1 << x)) continue;
            for(int c = 0; c < A; c++){
                for(int d = 0; d < A; d++){
                    res.ways[c][d] += a.ways[c][x] * b.ways[y][d];
                }
            }
        }
    }
    return res;
}

template<int A> using seg_info = optional<info<A>>;

template<int A> seg_info<A> info_op(seg_info<A> a, seg_info<A> b){
    if(!a) return b;
    if(!b) return a;
    return combine<A>(a.value(), b.value());
}

template<int A> seg_info<A> info_e(){
    return {};
}

template<int A> void solve(string str, vector<pair<int, char> > queries){
    int N = (int)str.size();
    int Q = (int)queries.size();
	// find a matrix
	// number of subsequences that end with b:
	// a, b, c -> a+b=c+1, b, c

	// 1, a, b, c
	// number of subsequences that appear exactly once:
	// a, b, c
	// all are ok except those which 
	// take letters: if you skipped a letter: track that
	// [not a] a [not a, b] b [not b, a] a [not a, c] c [not c]
	// [noa] A [noabw] 
	// A2 by A2
	// A2^3 multiplication

    vector<info<A>> letters(A);
    for(int c = 0; c < A; c++){
        letters[c].all_msk = (1 << c);
        for(int x = 0; x < A; x++) letters[c].pref_mask[x] = 0;
        for(int x = 0; x < A; x++) letters[c].suff_mask[x] = 0;
        for(int x = 0; x < A; x++) {
            for(int y = 0; y < A; y++){
                letters[c].ways[x][y] = 0;
            }
        }
        letters[c].ways[c][c] = 1;
    }
    vector<seg_info<A>> seg_init(N);
    for(int i = 0; i < N; i++) seg_init[i] = letters[str[i]-'a'];
    atcoder::segtree<seg_info<A>, info_op<A>, info_e<A>> seg(seg_init);

    constexpr int B2 = A+1;
    mat<B2> B_empty;
    for(int i = 0; i < B2; i++){
        for(int j = 0; j < B2; j++){
            B_empty[i][j] = 0;
        }
    }
    vector<mat<B2> > B_tr(A, B_empty);
    for(int i = 0; i < A; i++){
        for(int j = 0; j <= A; j++){
            B_tr[i][j][j] = 1;
            B_tr[i][j][i] = 1;
        }
    }
    vector<mat<B2>> B_init(N);
    for(int i = 0; i < N; i++){
        B_init[i] = B_tr[str[i]-'a'];
    }
    atcoder::segtree<mat<B2>, op<B2>, e<B2>> B_seg(B_init);

    auto get_cnt = [&]() -> num {
        info<A> res = seg.all_prod().value();
        num ans = 0;
        for(int x = 0; x < A; x++){
            for(int y = 0; y < A; y++){
                ans += res.ways[x][y];
            }
        }

        mat<B2> B_res = B_seg.all_prod();
        num all_cnt = 0;
        for(int i = 0; i < A; i++){
            all_cnt += B_res[A][i];
        }
        return all_cnt - ans;
    };

    for(int q = 0; q <= Q; q++){
        num x = get_cnt();
        cout << x << '\n';
        if(q < Q){
            auto [idx, c] = queries[q];
            seg.set(idx, letters[c-'a']);
            B_seg.set(idx, B_tr[c-'a']);
        }
    }
}

int main(){
	ios_base::sync_with_stdio(false), cin.tie(nullptr);
	int N, Q;
	cin >> N >> Q;
	string str;
	cin >> str;
    vector<pair<int, char> > queries(Q);
    char maxval = 'a';
    for(char c : str) maxval = max(maxval, c);
    for(int q = 0; q < Q; q++){
        int idx;
        cin >> idx;
        idx--;
        char c;
        cin >> c;
        queries[q] = {idx, c};
        maxval = max(maxval, c);
    }
    if(maxval == 'a' || maxval == 'b'){
        solve<2>(str, queries);
    } else if(maxval == 'c'){
        solve<3>(str, queries);
    } else if(maxval == 'd'){
        solve<4>(str, queries);
    } else if(maxval == 'e'){
        solve<5>(str, queries);
    } else {
        solve<6>(str, queries);
    }
}