#include <bits/stdc++.h>
using namespace std;
int n, p;
const int maxn = 100005;
unsigned int a[maxn << 1] = {1}, ans = 1;
char s[maxn];
int main() {
  cin >> n;
  if (n & 1)
    cout << "0" << endl;
  else {
    int m = n >> 1;
    cin >> s + 1;
    for (int i = 1; i <= n; i++)
      if (s[i] == '?') {
        for (int j = i >> 1; j >= i - m && j; j--) a[j] += a[j - 1];
      } else
        p++;
    for (int i = 1; i <= m - p; i++) ans = ans * 25;
    cout << (unsigned int)ans * a[m] << endl;
  }
  return 0;
}
