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

const int MOD = 98244353;
const int MAXN = 5e4 + 5;

int fib[MAXN];

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    fib[1] = 1;
    fib[0] = 0;
    for (int i = 2; i <= MAXN; i++) {
        fib[i] = (fib[i - 2] + fib[i - 1]) % MOD;
    }

    int n, q;
    cin >> n >> q;
    string s;
    cin >> s;
    int sz = 1;
    for (int i = 1; i < s.size(); i++) {
        if (s[i] != s[i - 1]) sz++;
    }
    vector <int> dp(n + 1, 0);
    int last_a = -1, last_b = -1;
    dp[0] = 1;
    for (int i = 1; i <= n; i++) {
        if (s[i - 1] == 'a') {
            if (last_a == -1) dp[i] = (dp[i - 1] * 2) % MOD;
            else {
                dp[i] = (2 * dp[i - 1]) % MOD;
                dp[i] = ((dp[i] - dp[last_a - 1]) % MOD + MOD) % MOD;
            } 
            last_a = i;
        } else {
            if (last_b == -1) dp[i] = (dp[i - 1] * 2) % MOD;
            else {
                dp[i] = (2 * dp[i - 1]) % MOD;
                dp[i] = ((dp[i] - dp[last_b - 1]) % MOD + MOD) % MOD;
            } 
            last_b = i;
        }
    }
    cout << ((dp[n] - 1 - (sz == 1 ? 1 : fib[sz + 2])) % MOD + MOD) % MOD << '\n';

    while (q--) {
        int idx;
        char c;
        cin >> idx >> c;
        idx--;

        if (s[idx] != c) {
            if (idx == 0) {
                if (s[idx + 1] == c) sz--;
                else sz++;
            } else if (idx == n - 1) {
                if (s[idx - 1] == c) sz--;
                else sz++;
            } else {
                if (s[idx - 1] == c && s[idx + 1] == c) sz -= 2;
                else if (s[idx] - 1 != c && s[idx + 1] != c) sz += 2;
            }
        }
        s[idx] = c;

        int last_a = -1, last_b = -1;
        for (int i = 1; i <= n; i++) {
            if (s[i - 1] == 'a') {
                if (last_a == -1) dp[i] = (dp[i - 1] * 2) % MOD;
                else {
                    dp[i] = (2 * dp[i - 1]) % MOD;
                    dp[i] = ((dp[i] - dp[last_a - 1]) % MOD + MOD) % MOD;
                } 
                last_a = i;
            } else {
                if (last_b == -1) dp[i] = (dp[i - 1] * 2) % MOD;
                else {
                    dp[i] = (2 * dp[i - 1]) % MOD;
                    dp[i] = ((dp[i] - dp[last_b - 1]) % MOD + MOD) % MOD;
                } 
                last_b = i;
            }
        }

        cout << ((dp[n] - 1 - (sz == 1 ? 1 : fib[sz + 2])) % MOD + MOD) % MOD << '\n';
    }
}