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#include <cstdio>
#include <map>
#include <string>
using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define PB push_back
#define INT(x) int x; scanf("%d", &x)
#define STR(n,x) char x[n]; scanf("%s", x)

const int mod = 998244353;
int n;
char a[50002];
map<string, int> s;
string x;

int go(int i = 0) {
	if (i == n) return ++s[x] == 2;
	if (!i) s.clear();
	int r = go(i + 1);
	x.PB(a[i]);
	r = (r + go(i + 1)) % mod;
	x.pop_back();
	return r;
}

int main() {
	INT(n1);
	n = n1;
	INT(q);
	scanf("\n");
	fgets(a, 50002, stdin);
	printf("%d\n", go());
	REP(qq,q) {
		INT(p);
		STR(2,z);
		a[p - 1] = z[0];
		printf("%d\n", go());
	}
}