#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using mint = atcoder::static_modint<998244353>;
// // using mint = atcoder::static_modint<1000000007>;
using ld = long double;
using ll = long long;
#define mp(a,b) make_pair(a,b)
#define rep(i,s,n) for(int i=s; i<(int)n; i++)
const vector<int> dx{1,0,-1,0},dy{0,1,0,-1};

int main(){
    int n,m;cin >> n >> m;
    string s;cin >> s;
    vector<vector<int>> G(n);
    rep(i,0,m){
        int a,b;cin >> a >> b;
        a--,b--;
        G[a].push_back(b);
        G[b].push_back(a);
    }
    int cnt=0;
    rep(i,0,n)if(s[i]=='?')cnt++;

    mint ans=0;
    mint h=mint(26).inv();
    rep(o,0,n)if(s[o]=='?' || s[o]=='o'){
        mint a=0;
        mint i=0;
        mint c=0;
        for(auto x:G[o]){
            if(s[x]=='a')a++;
            else if(s[x]=='i')i++;
            else c++;
        }
        mint add=0;
        //ai
        add+=a*i;

        //?i
        add+=h*c*i;

        //a?
        add+=h*a*c;

        //??
        add+=h*h*c*(c-1);

        if(s[o]=='?')add*=h;
        ans+=add;
    }

    ans*=mint(26).pow(cnt);
    cout << ans.val() << "\n";
}