#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  char str[100005];
  unsigned dp[50005] = {};
  scanf("%d %s", &n, str + 1);
  if (n % 2) {
    puts("0");
    return 0;
  }
  dp[0] = 1;
  for (int i = 1; i <= n; i++) {
    if (str[i] != '?') continue;
    for (int j = i / 2; j; j--) {
      dp[j] = dp[j] * 25u + dp[j - 1];
    }
    dp[0] = dp[0] * 25u;
  }
  printf("%u", dp[n / 2]);
}
