#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using mint = modint998244353;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  string s;
  cin >> s;
  mint inv26[10];
  inv26[0] = 1;
  rep(i, 9) inv26[i+1] = inv26[i] * mint(26).inv();
  VVI to(n);
  rep(_, m) {
    int a, b;
    cin >> a >> b;
    a--, b--;
    to[a].emplace_back(b);
    to[b].emplace_back(a);
  }
  mint ans;
  rep(u, n) if (s[u] == '?' || s[u] == 'o') {
    mint coeff = s[u] == '?' ? inv26[1] : 1;
    mint ca = 0, ci = 0, cq = 0;
    for (int v : to[u]) {
      if (s[v] == 'a') ca++;
      else if (s[v] == 'i') ci++;
      else if (s[v] == '?') cq++;
    }
    ans += coeff * ((ca + cq * inv26[1]) * (ci + cq * inv26[1]) - cq * inv26[2]);
  }
  ans *= mint(26).pow(count(all(s), '?'));
  cout << ans.val() << '\n';
}