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

#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) int((x).size())
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

#ifdef LOCAL
auto operator<<(auto& o, auto x) -> decltype(x.first, o);
auto operator<<(auto& o, auto x) -> decltype(x.end(), o) {
  o << "{";
  for (int i = 0; auto y : x) o << ", " + !i++ * 2 << y;
  return o << "}"; }
auto operator<<(auto& o, auto x) -> decltype(x.first, o) {
  return o << "(" << x.first << ", " << x.second << ")"; }
void __print(auto... x) { ((cerr << x << " "), ...) << endl; }
#define debug(x...) __print("[" #x "]:", x)
#else
#define debug(...) 2137
#endif

template<int M, int R>
struct Mod {
  static const int mod = M, rt = R;
  int x;
  Mod(ll y = 0) : x(y % M) { x += (x < 0) * M; }
  Mod& operator+=(Mod o) {
    if ((x += o.x) >= M) x -= M;
    return *this; }
  Mod& operator-=(Mod o) {
    if ((x -= o.x) < 0) x += M;
    return *this; }
  Mod& operator*=(Mod o) {
    x = 1ll * x * o.x % M;
    return *this; }
  Mod& operator/=(Mod o) { return *this *= o.inv(); }
  friend Mod operator+(Mod a, Mod b) { return a += b; }
  friend Mod operator-(Mod a, Mod b) { return a -= b; }
  friend Mod operator*(Mod a, Mod b) { return a *= b; }
  friend Mod operator/(Mod a, Mod b) { return a /= b; }
  auto operator<=>(const Mod&) const = default;
  Mod pow(ll n) const {
    Mod a = x, b = 1;
    for (; n; n /= 2, a *= a) if (n % 2) b *= a;
    return b; }
  Mod inv() const { assert(x); return pow(M - 2); }
  friend ostream& operator<<(ostream& os, Mod x) {
    return os << x.x; }
};
using mint = Mod<998244353, 3>;

mint comp(string& s) {
  const int num = 6;
  int n = s.length();
  vector<mint> dp_dist(n + 1), dp_unq(n + 1);
  dp_dist[0] = dp_unq[0] = 1;
  vector<int> last(num + 1, -1);
  last[num] = 0;
  for(int i = 1; i <= n; i++) {
    int ind = s[i - 1] - 'a';
    int lst = last[ind];
    for(int j = 0; j <= num; j++) {
      if(last[j] >= lst && last[j] != -1) {
        dp_unq[i] += dp_unq[last[j]];
      }
    }
    dp_dist[i] = 2 * dp_dist[i - 1];
    if(lst != -1) dp_dist[i] -= dp_dist[lst - 1];
    last[ind] = i;
  }
  mint res = dp_dist[n];
  for(int i = 0; i <= num; i++) {
    int lst = last[i];
    if(lst != -1) res -= dp_unq[lst];
  }
  return res;
}

template<int num>
struct seg_dist {
  using mat = array<array<mint, num + 1>, num + 1>;
  vector<mat> t;
  int n;
  seg_dist(int nn) {
    n = 1;
    while(n < nn) n *= 2;
    mat id = {};
    for(int i = 0; i <= num; i++) id[i][i] = 1;
    t.assign(2 * n, id);
  }
  void init(int i, int x) {
    mat& m = t[i];
    m = {};
    for(int j = 0; j < num; j++) m[j][j] = 1;
    m[x][x] = 0;
    m[x][num] = 1;
    m[num][num] = 2;
    m[num][x] = -1;
  }
  void build(string& s) {
    for(int i = 0; i < s.length(); i++) {
      init(i + n, s[i] - 'a');
    }
    for(int i = n - 1; i > 0; i--) {
      t[i] = merge(t[2 * i + 1], t[2 * i]);
    }
  }
  void upd(int i, int x) {
    i += n;
    init(i, x);
    while(i /= 2) t[i] = merge(t[2 * i + 1], t[2 * i]);
  }
  mint get() {
    return t[1][num][num];
  }
  mat merge(const mat& a, const mat& b) {
    mat c = {};
    for(int i = 0; i <= num; i++) {
      for(int k = 0; k <= num; k++) {
        for(int j = 0; j <= num; j++) {
          c[i][j] += a[i][k] * b[k][j];
        }
      }
    }
    return c;
  }
};

template<int num>
struct seg_unq {
  static constexpr int sz = (num + 1) * (num + 1);
  using mat = array<array<mint, sz>, sz>;
  vector<mat> t;
  int n;
  seg_unq(int nn) {
    n = 1;
    while(n < nn) n *= 2;
    mat id = {};
    for(int i = 0; i < sz; i++) id[i][i] = 1;
    t.assign(2 * n, id);
  }
  void init(int i, int x) {
    mat& m = t[i];

    m = {};

    for(int j = 0; j < sz; j++) {
      m[j][j] = 1;
    }
    int ind_unq = num * (num + 1) + x;
    m[ind_unq][ind_unq] = 0;
    for(int j = 0; j <= num; j++) {
      m[ind_unq][x * (num + 1) + j] = 1;
    }

    for(int j = 0; j < num; j++) {
      if(j != x) {
        int id = x * (num + 1) + j;
        m[id][id] = 0;
      }
      int id = j * (num + 1) + x;
      m[id][id] = 0;
      for(int k = 0; k <= num; k++) {
        m[id][x * (num + 1) + k] = 1;
      }
    }
    int id = x * (num + 1) + num;
    m[id][id] = 0;
  }
  void build(string& s) {
    for(int i = 0; i < s.length(); i++) {
      init(i + n, s[i] - 'a');
    }
    for(int i = n - 1; i > 0; i--) {
      t[i] = merge(t[2 * i + 1], t[2 * i]);
    }
  }
  void upd(int i, int x) {
    i += n;
    init(i, x);
    while(i /= 2) t[i] = merge(t[2 * i + 1], t[2 * i]);
  }
  mint get() {
    mint res = 0;
    for(int i = 0; i <= num; i++) {
      int id1 = num * (num + 1) + i;
      for(int j = 0; j <= num; j++) {
        int id2 = j * (num + 1) + num;
        res += t[1][id1][id2];
      }
    }
    return res;
  }
  mat merge(const mat& a, const mat& b) {
    mat c = {};
    for(int i = 0; i < sz; i++) {
      for(int k = 0; k < sz; k++) {
        for(int j = 0; j < sz; j++) {
          c[i][j] += a[i][k] * b[k][j];
        }
      }
    }
    return c;
  }
};

int main() {
  cin.tie(0)->sync_with_stdio(0);

  int n, q;
  cin >> n >> q;
  string s;
  cin >> s;

  bool f = 1;
  for(char c : s) {
    if(c != 'a' && c != 'b') f = 0;
  }
  vector<pair<int, int>> op(q);
  for(int i = 0; i < q; i++) {
    int id;
    char c;
    cin >> id >> c;
    op[i] = {id - 1, c - 'a'};
    if(c != 'a' && c != 'b') f = 0;
  }

  if(f) {
    seg_dist<2> dist(n);
    seg_unq<2> unq(n);
    dist.build(s);
    unq.build(s);
    cout << dist.get() - unq.get() << '\n';
    for(int i = 0; i < q; i++) {
      auto [id, x] = op[i];
      dist.upd(id, x);
      unq.upd(id, x);
      cout << dist.get() - unq.get() << '\n';
    }
  } else {
    cout << comp(s) << '\n';
    for(int i = 0; i < q; i++) {
      auto [id, x] = op[i];
      s[id] = 'a' + x;
      cout << comp(s) << '\n';
    }
  }
}