//pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include "atcoder/all"
using namespace std;
typedef long long ll;
const int INF = 1<<30;
const ll INFLL = 1LL<<60;
const ll MOD = 998244353;
const double INFD = 1.0E10;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, -1, 0, 1};
//const int dx[8] = {1, 1, 0, -1, -1, -1, 0, 1};
//const int dy[8] = {0, 1, 1, 1, 0, -1, -1, -1};
using Pair = pair<ll, ll>;
using Graph = vector<vector<int>>;
using mint = atcoder::modint998244353;




int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);
    int n, m; cin >> n >> m;
    string s; cin >> s;
    Graph G(n);
    for (int i = 0; i < m; i++){
        int u, v; cin >> u >> v; u--; v--;
        G[u].push_back(v);
        G[v].push_back(u);
    }
    
    ll cnt_q = 0;
    for (auto c : s){
        if (c == '?') cnt_q++;
    }
    
    vector<mint> row26(6001);
    for (ll i = 0; i < 6000; i++){
        row26[i] = mint(26).pow(i);
    }
    
    mint ans = 0;
    //vector<tuple<int, int, int>> vec;
    for (int i = 0; i < n; i++){
        if (s[i] != 'a' && s[i] != '?') continue;
        for (auto j : G[i]){
            if (s[j] != 'o' && s[j] != '?') continue;
            
            for (auto k : G[j]){
                if (i == k) continue;
                if (s[k] != 'i' && s[k] != '?') continue;
                ll tmpcnt = cnt_q;
                if (s[i] == '?') tmpcnt--;
                if (s[j] == '?') tmpcnt--;
                if (s[k] == '?') tmpcnt--;
                //vec.push_back({i, j, k});
                //cout << i << j << k << ' ' << tmpcnt << endl;
                ans += row26[tmpcnt];
            }
        }
    }
    
    cout << ans.val() << endl;

    return 0;
}