#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)
#define all(a) (a).begin(),(a).end()

#include <atcoder/modint>
using namespace atcoder;
using mint = modint998244353;

int main() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    
    int N, M;
    string S;
    cin >> N >> M >> 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;
    rep(v, 0, N) if (S[v] == 'o' || S[v] == '?') {
        mint cntA = 0, cntI = 0, cntX;
        int cntXt = 0;
        for (int next : G[v]) {
            if (S[next] == 'a') ++cntA;
            if (S[next] == 'i') ++cntI;
            if (S[next] == '?') ++cntXt;
        }
        cntX = cntXt;
        
        if (S[v] == 'o') {
            ans += cntA * cntI * mint(26).pow(cnt);
            if (cntXt >= 1) ans += cntA * cntX * mint(26).pow(cnt - 1);
            if (cntXt >= 1) ans += cntI * cntX * mint(26).pow(cnt - 1);
            if (cntXt >= 2) ans += cntX * (cntX - 1) * mint(26).pow(cnt - 2);
        } else {
            ans += cntA * cntI * mint(26).pow(cnt - 1);
            if (cntXt >= 1) ans += cntA * cntX * mint(26).pow(cnt - 2);
            if (cntXt >= 1) ans += cntI * cntX * mint(26).pow(cnt - 2);
            if (cntXt >= 2) ans += cntX * (cntX - 1) * mint(26).pow(cnt - 3);
        }
    }
    cout << ans.val() << '\n';
}