//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (ll)(n); i++)
#define all(a) (a).begin(), (a).end()
using ll = long long;
const int INF32 = 2e9;
const ll INF64 = 4e18;
const ll MOD = 998244353;
vector<ll> P26={1};
ll power26(int x){
    while(P26.size()<=x){
        P26.push_back(P26[P26.size()-1]*26%MOD);
    }
    return P26[x];
}


int main() {
    int N, M;
    string S;
    cin >> N >> M >> S;
    vector<vector<int>> G(N,vector<int>(0));
    int questioncnt = 0;
    rep(i,N){
        if(S[i]=='?')questioncnt++;
    }
    rep(i,M){
        int Ai, Bi;
        cin >> Ai >> Bi;
        Ai--;Bi--;
        G[Ai].push_back(Bi);
        G[Bi].push_back(Ai);
    }
    ll ans = 0;
    rep(i,N){
        if (!(S[i]=='?'||S[i]=='o'))continue;
        int x26_1 = questioncnt;
        if(S[i]=='?')x26_1--;
        for(int j = 0; j < G[i].size(); j++){
            for(int k = j+1; k < G[i].size(); k++){
                int x26_2 = x26_1;
                if(!(S[G[i][j]]=='a'||S[G[i][j]]=='i'||S[G[i][j]]=='?'))continue;
                if(!(S[G[i][k]]=='a'||S[G[i][k]]=='i'||S[G[i][j]]=='?'))continue;
                if((S[G[i][j]]=='a'||S[G[i][j]]=='i')&&S[G[i][j]]==S[G[i][k]])continue;
                if(S[G[i][j]]=='?')x26_2--;
                if(S[G[i][k]]=='?')x26_2--;
                if(S[G[i][k]]=='?'&&S[G[i][j]]=='?'){
                    ans += 2*power26(x26_2);
                    ans %= MOD;
                }
                else {
                    ans += power26(x26_2);
                    ans %= MOD;
                }
            }
        }
    }
    cout << ans << endl;
    return 0;
}