#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
unsigned int dp[N];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  int n, cnt = 0;
  cin >> n;
  string s;
  cin >> s;
  if (n % 2 == 1) {
    cout << 0 << '\n';
    return 0;
  }
  dp[0] = 1;
  for (int i = 0; i < n; i++) {
    if (s[i] != '?')
      cnt++;
    else {
      for (int j = (i + 1) / 2; j > 0; j--) dp[j] = dp[j] + dp[j - 1];
    }
  }
  unsigned int ans = dp[n / 2];
  for (int i = 0; i < n / 2 - cnt; i++) ans *= 25;
  cout << ans << '\n';
}
