#include <bits/stdc++.h>
using namespace std;
 
#include <atcoder/all>
using namespace atcoder;
 
#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
 
#define FASTIO cin.tie(0)->sync_with_stdio(0)
 
using ll = long long;
using mint = modint998244353;

int main() {
  FASTIO;
  int N, M;
  string S;
  cin >> N >> M >> S;
  vector<unordered_set<int>> G(N);
  for(int i = 0; i < M; ++i) {
    int a, b;
    cin >> a >> b;
    a--, b--;
    G[a].insert(b);
    G[b].insert(a);
  }
  int q = 0;
  for(int i = 0; i < N; ++i) {
    if(S[i] == '?') ++q;
  }
  vector<mint> pw(N + 1, 1);
  for(int i = 0; i < N; ++i) {
    pw[i + 1] = pw[i] * 26;
  }
  mint ans;
  for(int i = 0; i < N; ++i) {
    for(int j = 0; j < N; ++j) {
      if(i == j) continue;
      if(S[i] != 'a' && S[i] != '?') continue;
      if(S[j] != 'i' && S[j] != '?') continue;
      int co = 0, cq = 0;
      int s = (G[i].size() < G[j].size() ? i : j);
      int t = i + j - s;
      for(const int &k : G[s]) {
        if(!G[t].count(k)) continue;
        if(S[k] == 'o') ++co;
        if(S[k] == '?') ++cq;
      }
      int q2 = q - cq - (S[i] == '?') - (S[j] == '?');
      if(cq == 0) {
        ans += pw[q2] * co;
      }else {
        ans += pw[q2] * pw[cq - 1] * (26 * co + cq);
      }
    }
  }
  cout << ans.val() << endl;
}