#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
	int N,M;
	cin>>N>>M;
	string S;
	cin>>S;
	int ans = 0, mod = 998244353;
	vector<int> I(N+1);
	I[0] = 1;
	for(int i=0;i<N;i++) I[i+1] = I[i]*26%mod;
	vector<vector<int>> G(N);
	for(int i=0;i<M;i++){
		int a,b;
		cin>>a>>b;
		a--;
		b--;
		G[a].push_back(b);
		G[b].push_back(a);
	}
	int ct = 0;
	for(char c:S) ct += (c == '?');
	for(int i=0;i<N;i++)for(int x:G[i])for(int y:G[i])if(x != y){
		int now = ct;
		if(S[i] == '?') now--;
		else if(S[i] != 'o') continue;
		if(S[x] == '?') now--;
		else if(S[x] != 'a') continue;
		if(S[y] == '?') now--;
		else if(S[y] != 'i') continue;
		ans += I[now];
		ans %= mod;
	}
	cout<<ans<<endl;
}