#include <bits/stdc++.h>
using namespace std;
unsigned dp[100010];
int n, tmp;
string s;
int main() {
  cin >> n;
  cin >> s;
  int m = n / 2;
  int tmp = 0;
  if (n % 2 == 1) {
    cout << 0;
    return 0;
  }
  dp[0] = 1;
  for (int i = 1; i <= n; i++)
    if (s[i - 1] == '?')
      for (int j = i / 2; j && j >= (i - m); j--) dp[j] += dp[j - 1];
    else
      tmp++;
  unsigned res = dp[m];
  for (int i = 0; i < m - tmp; i++) res *= 25;
  cout << res;
  return 0;
}
