#include <bits/stdc++.h>
using namespace std;
int n;
unsigned int f[100011];
int main() {
  scanf("%d", &n);
  if (n & 1) {
    printf("0\n");
    return 0;
  }
  f[0] = 1;
  char ch = getchar();
  for (int i = 1; i <= n; i++) {
    if (getchar() == '?') {
      for (int j = i & 1; j <= i; j += 2) f[j] = f[j - 1] * 25 + f[j + 1];
    } else {
      for (int j = i & 1; j <= i; j += 2) f[j] = f[j - 1];
    }
  }
  printf("%u\n", f[0]);
  return 0;
}
