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#include "bits/stdc++.h"
using namespace std;
#define rep(i,a,b) for(int i=(a); i<(b); ++i)
#define all(x) x.begin(),x.end()
#define sz(x) int(x.size())
typedef long long ll;
typedef long long ull;
typedef vector<int> vi;
typedef vector<vi> vvi;

const int nchar = 2;
const int B = nchar+1;
const ull mod = 998244353;
ull mul(ull a, ull b){
    return a*b%mod;
}

// van I naar J
struct matrix{
    int M[B][B];
    matrix() {
        rep(i,0,B) rep(j,0,B) M[i][j] = 0;
        rep(i,0,B) M[i][i] = 1;
    }
    void initAll(int pos){
        rep(i,0,B) rep(j,0,B) M[i][j] = 0;

        M[B-1][B-1] = 2;
        // naar zelf
        rep(i,0,nchar) M[i][i] = 1;
        M[pos][pos] = 0;
        
        M[B-1][pos] = 1;
        M[pos][B-1] = -1;
    }
    void init0(int pos){
        rep(i,0,B) rep(j,0,B) M[i][j] = 0;

        rep(i,0,B) rep(j,0,B) M[i][j] = 0;

        M[B-1][B-1] = 2;
        // naar zelf
        rep(i,0,nchar) M[i][i] = 1;
        M[pos][pos] = 0;
        
        M[B-1][pos] = 1;
        M[pos][B-1] = -2;
    }


    ull getAns(){
        return M[B-1][B-1];
    }
    matrix operator*(const matrix& b){
        matrix res = matrix();
        rep(i,0,B) rep(j,0,B){
            ull sm = 0;
            rep(k,0,B) {
                sm += (ull)M[i][k]*b.M[k][j];
            }
            res.M[i][j] = sm % mod;;
        }
        return res;
    }
    void print(){
        rep(i,0,B){
            if (i%nchar == 0 and i) cout << string(2+B*5, '-') << '\n';
            rep(j,0,B) {
                if (j%nchar==0 and j) cout << '|';
                cout << string(4-sz(to_string(M[j][i])),' ') << to_string(M[j][i]) << ' ';
            }
            cout << '\n';
        }cout << endl;
    }
};

int brute(string a){
    map<string,int> mp;
    rep(i,0,1<<sz(a)){
        string cur;
        rep(j,0,sz(a)) if (i&(1<<j)){
            cur += a[j];
        }
        mp[cur]++;
    }
    int ans = 0;
    for(auto [k,v] : mp){
        ans += v>1;
    }
    return ans;
}

// alle a -> b maakt niks uit -> 2^b
// niet alle a-> alle b's geforceerd in de gaps
// 

// [2,4,6,9,14,22,35,56,90,145]
// a[i] = a[i-1] + a[i-2] - 1 for i > 

const int N = 100000;
ll tab[N];

struct TreeAll {
	typedef matrix T;
	T f(T& a, T& b) { return a*b; } // (any associative fn)
	vector<T> s; int n;
	TreeAll(int n = 0) : s(2*n, matrix()), n(n) {}
	void update(int i, int pos) {
		for (s[i += n].initAll(pos); i /= 2;)
			s[i] = f(s[i * 2], s[i * 2 + 1]);
	}
	T query(int b, int e) { // query [b, e)
		T ra = matrix(), rb = matrix();
		for (b += n, e += n; b < e; b /= 2, e /= 2) {
			if (b % 2) ra = f(ra, s[b++]);
			if (e % 2) rb = f(s[--e], rb);
		}
		return f(ra, rb);
	}
};

struct Tree0 {
	typedef matrix T;
	T f(T& a, T& b) { return a*b; } // (any associative fn)
	vector<T> s; int n;
	Tree0(int n = 0) : s(2*n, matrix()), n(n) {}
	void update(int i, int pos) {
		for (s[i += n].init0(pos); i /= 2;)
			s[i] = f(s[i * 2], s[i * 2 + 1]);
	}
	T query(int b, int e) { // query [b, e)
		T ra = matrix(), rb = matrix();
		for (b += n, e += n; b < e; b /= 2, e /= 2) {
			if (b % 2) ra = f(ra, s[b++]);
			if (e % 2) rb = f(s[--e], rb);
		}
		return f(ra, rb);
	}
};

int main(){
    // matrix mat;
    // mat.init(3);
    // mat.print();


    cin.tie(NULL),cin.sync_with_stdio(false);

    tab[0] = 1;
    tab[1] = 2;
    tab[2] = 4;
    tab[3] = 6;
    tab[4] = 9;

    rep(i,5,N){
        tab[i] = (tab[i-1] + tab[i-2] - 1)%mod;
        if (tab[i] < 0) tab[i] += mod;
    }


    int n,q; cin >> n >> q;
    TreeAll segAll(n);
    // Tree0 seg0(n);

    string s; cin >> s;

    // count initial number of blocks
    int blocks = 1;
    rep(i,1,n){
        blocks += s[i] != s[i-1];
    }

    // 

    rep(i,0,n) {
        segAll.update(i,s[i]-'a');
    }

    cout << (segAll.query(0,n).getAns() + mod - tab[blocks])%mod << '\n';


    while(q--){
        int i; cin >> i; --i;
        char c; cin >> c;
        int pos = c-'a';
        
        if (c != s[i]){
            segAll.update(i,pos);

            // update number of blocks
            if (i==0){
                if (s[i] != s[i+1]){
                    blocks -= 1;
                }else{
                    blocks += 1;
                }
            }else if (i+1==n){
                if (s[i] != s[i-1]){
                    blocks -= 1;
                }else{
                    blocks += 1;
                }
            }else{
                if (s[i-1] == s[i+1]){
                    if (s[i] != s[i+1]){
                        blocks -= 2;
                    }else{
                        blocks += 2;
                    }
                }
            }
            s[i] = c;
        }

        cout << (segAll.query(0,n).getAns() + mod - tab[blocks])%mod << '\n';
    }
    // cout << brute(s) << '\n';
}

/*

*/