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

typedef pair<int, char> par;
vector<par> req;
string s;
int N, n, dp[7][3][7], istaken[6], ones[6];
const int M = 998244353;

void solve()
{
	int wyn = 0, a, newone, newtwo;
	for(int i=0; i<N; i++) for(int j=1; j<3; j++) for(int k=0; k<N; k++) dp[i][j][k] = 0;
	for(int i=0; i<N; i++) istaken[i] = ones[i] = 0;
	for(int i=0; i<s.size(); i++) {
		a = s[i] - 'a';
		newone = newtwo = 0;
		wyn = (wyn + ones[a]) % M;
		ones[a] = 0;
		for(int j=0; j<N; j++) {
			newone = (newone + dp[j][1][a]) % M;
			newtwo = (newtwo + dp[j][2][a]) % M;
			wyn = (wyn + dp[j][2][a]) % M;
			ones[a] = (ones[a] + dp[j][1][a]) % M;
			dp[j][1][a] = dp[j][2][a] = 0;
		}
		for(int j=0; j<N; j++) {
			dp[a][2][j] = (((dp[a][2][j] + dp[a][1][j]) % M) + newtwo) % M;
			dp[a][1][j] = newone;
		}
		if(istaken[a] == 0) {
			for(int j=0; j<N; j++) dp[a][1][j]++;
			istaken[a] = 1;
		}
		else if(istaken[a] == 1) {
			wyn = (wyn + 1) % M;
			istaken[a] = 2;
		}
	}
	cout<<wyn<<'\n';
	return;
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0);
	int q, a;
	char c;
	cin>>n>>q>>s;
	for(int i=0; i<s.size(); i++) if(s[i] - 'a' > N) N = s[i] - 'a';
	for(int i=1; i<=q; i++) {
		cin>>a>>c;
		if(c - 'a' > N) N = c - 'a';
		req.push_back(par(a, c));
	}
	N++;
	solve();
	for(int i=0; i<q; i++) {
		s[req[i].first-1] = req[i].second;
		solve();
	}
    return 0;
}