#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int n, p;
char c[N];
unsigned int f[N * 2], ans = 1;
int main() {
  scanf("%d", &n);
  if (n & 1) {
    printf("0");
    return 0;
  } else {
    f[0] = 1;
    int m = n / 2;
    cin >> c + 1;
    for (int i = 1; i <= n; i++)
      if (c[i] == '?')
        for (int j = i / 2; j >= i - m && j; j--) f[j] += f[j - 1];
      else
        p++;
    for (int i = 1; i <= m - p; i++) ans *= 25;
    cout << (unsigned int)ans * f[m];
  }
  return 0;
}
