#include <bits/stdc++.h>
using namespace std;
int n;
unsigned f[100010];
int main() {
  scanf("%d\n", &n);
  if (n & 1) {
    puts("0");
    return 0;
  }
  int m = n / 2, chn = m;
  f[0] = 1;
  for (int i = 1; i <= n; ++i)
    if (getchar() == '?') {
      for (int j = i / 2; j >= m - (n - i) && j; --j) f[j] += f[j - 1];
    } else
      --chn;
  while (chn-- > 0) f[m] *= 25;
  printf("%u\n", f[m]);
}
