#include <bits/stdc++.h>
using namespace std;
unsigned int dp[410000];
char s[210000];
int main() {
  int n, i, j;
  cin >> n;
  scanf("%s", s);
  if (n & 1)
    puts("0");
  else {
    n /= 2;
    dp[n * 2 + 1] = 1;
    int num = n;
    for (i = 0; s[i]; i++) {
      if (s[i] == '?') {
        int t = min(i, n);
        for (j = (n << 1); j <= t + (n << 1); j++)
          dp[j - i] += dp[j - (i - 1) + 1];
      } else
        num--;
    }
    unsigned int ans = dp[1];
    while (num--) ans *= 25;
    cout << ans << endl;
  }
}
