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