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#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=(a);i<(n);i++)
#define per(i,a,n) for (int i=(n)-1;i>=(a);i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef long double db;
mt19937 mrand(1111); 
const ll mod=998244353;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=50100;
int dp[N],lst[10];
int n,q,a[N];
char s[N],t[10];
struct node {
	int pre[6],suf[6];
	int seq[6][6];
	ll mat[7][7];
}nd[N*4];
ll tmp[10][10],tmp2[10][10];
void upd(int p) {
	rep(i,0,6) {
		nd[p].pre[i]=min(nd[p+p].pre[i],nd[p+p+1].pre[i]);
		nd[p].suf[i]=max(nd[p+p].suf[i],nd[p+p+1].suf[i]);
	}
	rep(i,0,6) rep(j,0,6) tmp[i][j]=0;
	rep(i,0,6) rep(j,0,6) if (nd[p+p].seq[i][j]) {
		rep(k,0,6) if (nd[p+p+1].pre[k]<=n&&nd[p+p].suf[k]<=nd[p+p].suf[j]
			&&nd[p+p+1].pre[k]<=nd[p+p+1].pre[j]) {
			tmp[i][k]+=nd[p+p].seq[i][j];
		}
	}
	rep(i,0,6) rep(k,0,6) tmp[i][k]%=mod;
	rep(i,0,6) rep(k,0,6) {
		tmp2[i][k]=(tmp[i][0]*nd[p+p+1].seq[0][k]+tmp[i][1]*nd[p+p+1].seq[1][k]+tmp[i][2]*nd[p+p+1].seq[2][k]+
		tmp[i][3]*nd[p+p+1].seq[3][k]+tmp[i][4]*nd[p+p+1].seq[4][k]+tmp[i][5]*nd[p+p+1].seq[5][k])%mod;
	}
	rep(i,0,6) rep(j,0,6) if (nd[p+p].seq[i][j]&&nd[p+p+1].pre[j]>n) {
		tmp2[i][j]=(tmp2[i][j]+nd[p+p].seq[i][j]);
	}
	rep(i,0,6) rep(j,0,6) if (nd[p+p+1].seq[i][j]&&nd[p+p].pre[i]>n) {
		tmp2[i][j]=(tmp2[i][j]+nd[p+p+1].seq[i][j]);
	}
	rep(i,0,6) rep(j,0,6) nd[p].seq[i][j]=tmp2[i][j]%mod;

	rep(i,0,6) rep(j,0,6) tmp[i][j]=0;
	rep(i,0,6) rep(j,0,6) if (nd[p+p].seq[i][j]) {
		rep(k,0,6) if (nd[p+p+1].pre[k]<=n&&nd[p+p].suf[k]<=nd[p+p].suf[j]
			&&nd[p+p+1].pre[k]<=nd[p+p+1].pre[j]) {
			tmp[i][k]+=nd[p+p].seq[i][j];
		}
	}
	rep(i,0,6) rep(k,0,6) tmp[i][k]%=mod;
	rep(i,0,6) rep(k,0,6) {
		tmp2[i][k]=(tmp[i][0]*nd[p+p+1].seq[0][k]+tmp[i][1]*nd[p+p+1].seq[1][k]+tmp[i][2]*nd[p+p+1].seq[2][k]+
		tmp[i][3]*nd[p+p+1].seq[3][k]+tmp[i][4]*nd[p+p+1].seq[4][k]+tmp[i][5]*nd[p+p+1].seq[5][k])%mod;
	}
	rep(i,0,6) rep(j,0,6) if (nd[p+p].seq[i][j]&&nd[p+p+1].pre[j]>n) {
		tmp2[i][j]=(tmp2[i][j]+nd[p+p].seq[i][j]);
	}
	rep(i,0,6) rep(j,0,6) if (nd[p+p+1].seq[i][j]&&nd[p+p].pre[i]>n) {
		tmp2[i][j]=(tmp2[i][j]+nd[p+p+1].seq[i][j]);
	}
	rep(i,0,6) rep(j,0,6) nd[p].seq[i][j]=tmp2[i][j]%mod;
	rep(i,0,7) rep(j,0,7) {
		nd[p].mat[i][j]=(nd[p+p].mat[i][0]*nd[p+p+1].mat[0][j]+nd[p+p].mat[i][1]*nd[p+p+1].mat[1][j]+
		nd[p+p].mat[i][2]*nd[p+p+1].mat[2][j]+nd[p+p].mat[i][3]*nd[p+p+1].mat[3][j]+
		nd[p+p].mat[i][4]*nd[p+p+1].mat[4][j]+nd[p+p].mat[i][5]*nd[p+p+1].mat[5][j]+
		nd[p+p].mat[i][6]*nd[p+p+1].mat[6][j])%mod;
	}
}
void build(int p,int l,int r) {
	if (l==r) {
		rep(i,0,6) nd[p].pre[i]=n+1,nd[p].suf[i]=0;
		rep(i,0,6) rep(j,0,6) nd[p].seq[i][j]=0;
		rep(i,0,7) rep(j,0,7) nd[p].mat[i][j]=(i==j);
		rep(i,0,7) nd[p].mat[i][a[l]]=1;
		nd[p].seq[a[l]][a[l]]=1;
		nd[p].suf[a[l]]=l;
		nd[p].pre[a[l]]=l;
	} else {
		int md=(l+r)>>1;
		build(p+p,l,md);
		build(p+p+1,md+1,r);
		upd(p);
	}
}

void change(int p,int l,int r,int x,int v) {
	if (l==r) {
		a[x]=v;
		rep(i,0,6) nd[p].pre[i]=n+1,nd[p].suf[i]=0;
		rep(i,0,6) rep(j,0,6) nd[p].seq[i][j]=0;
		rep(i,0,7) rep(j,0,7) nd[p].mat[i][j]=(i==j);
		rep(i,0,7) nd[p].mat[i][a[x]]=1;
		nd[p].seq[a[x]][a[x]]=1;
		nd[p].suf[a[x]]=x;
		nd[p].pre[a[x]]=x;
	} else {
		int md=(l+r)>>1;
		if (x<=md) change(p+p,l,md,x,v);
		else change(p+p+1,md+1,r,x,v);
		upd(p);
	}
}

int query() {
	int ans1=0;
	int ans2=0;
	rep(i,0,6) ans1=(ans1+nd[1].mat[6][i])%mod;
	rep(i,0,6) rep(j,0,6) ans2=(ans2+nd[1].seq[i][j])%mod;
	ans1=(ans1+mod-ans2)%mod;
	return ans1;
}
int main() {
	scanf("%d%d",&n,&q);
	scanf("%s",s+1);
	rep(i,1,n+1) a[i]=s[i]-'a';
	build(1,1,n);
	printf("%d\n",query());
	rep(i,0,q) {
		int x;
		scanf("%d%s",&x,t);
		change(1,1,n,x,t[0]-'a');
		printf("%d\n",query());
	}

}