#include <bits/stdc++.h>
using namespace std;
int n;
char s[100010];
unsigned int dp[50010];
int main() {
  int n, i, j;
  cin >> n;
  if (n % 2 == 1) {
    cout << "0" << endl;
    return 0;
  } else {
    cin >> s + 1;
    int m = n / 2;
    int sum = 0;
    dp[0] = 1;
    for (i = 1; i <= n; i++) {
      if (s[i] == '?') {
        for (j = i / 2; j >= i - m && j; j--) dp[j] += dp[j - 1];
      } else
        sum++;
    }
    unsigned int ans = dp[n / 2];
    for (i = 1; i <= (n - 2 * sum) / 2; i++) ans *= 25;
    cout << ans << endl;
  }
  return 0;
}
