#include <bits/stdc++.h>
using namespace std;

using ll = long long;

int main()
{
    int N, M;
    cin >> N >> M;
    string S;
    cin >> S;

    assert(1 <= N && N <= 6000);
    assert(0 <= M && M <= 6000);
    assert(S.size() == N);
    
    const ll MOD = 998244353LL;

    vector<ll> power26(M + 1);
    power26[0] = 1LL;
    for (int i = 1; i <= M; i++)
    {
        power26[i] = (power26[i - 1] * 26LL) % MOD;
    }

    vector<vector<int>> g(N, vector<int>());

    for (int i = 0; i < M; i++)
    {
        int a, b;
        cin >> a >> b;
        assert(1 <= a && a <= N);
        assert(1 <= b && b <= N);
        assert(a < b);

        a--;
        b--;

        g[a].push_back(b);
        g[b].push_back(a);
    }

    ll q = 0;
    for (int i = 0; i < N; i++)
    {
        if (S[i] == '?')
        {
            q++;
        }
    }

    ll ans = 0;
    for (int i = 0; i < N; i++)
    {
        vector<int>& n = g[i];
        if (S[i] == 'o' || S[i] == '?')
        {
            for (int j = 0; j < n.size(); j++)
            {
                for (int k = 0; k < n.size(); k++)
                {
                    if (j == k) continue;

                    ll c = 0;
                    if (S[n[j]] == '?') c++;
                    else if (S[n[j]] != 'a') continue;
                    
                    if (S[n[k]] == '?') c++;
                    else if (S[n[k]] != 'i') continue;

                    if (S[i] == '?') c++;

                    ans += power26[q - c];
                    ans %= MOD;
                }
            }
        }
    }

    cout << ans << endl;
}