#include <bits/stdc++.h>
using namespace std;
int k, i, n, j, L, R;
char s[100001];
unsigned int dp[100001];
int main() {
  scanf("%d", &n);
  scanf("%s", s);
  dp[100000] = 1;
  L = R = 100000;
  for (i = 1; i <= n; i++) {
    L--;
    if (s[i - 1] == '?')
      for (j = L; j <= R; j++) dp[j] = dp[j] * 25 + dp[j + 2];
    while (R - L > n - i) {
      dp[R] = 0;
      R--;
    }
  }
  cout << dp[L];
  return 0;
}
