#include <bits/stdc++.h>
using namespace std;
int n, p;
unsigned int r = 1, f[200010];
char c[200010];
signed main() {
  cin >> n;
  if (n & 1)
    puts("0");
  else {
    f[0] = 1;
    cin >> c + 1;
    for (int i = 1; i <= n; i++) {
      if (c[i] == '?')
        for (int j = i / 2; j >= i - n / 2 && j; j--) f[j] += f[j - 1];
      else
        p++;
    }
    for (int i = 1; i + p <= n / 2; i++) r *= 25;
    cout << (unsigned int)r * f[n / 2] << '\n';
  }
}
