#include <bits/stdc++.h>
using namespace std;
int n;
char s[100005];
int f[100005];
int main() {
  scanf("%d", &n);
  if (n & 1) {
    printf("0\n");
    return 0;
  }
  scanf("%s", s + 1);
  int cnt = 0;
  f[0] = 1;
  int k = n / 2;
  for (int i = 1; i <= n; i++) {
    if (s[i] == '?') {
      if (!(i & 1)) f[0] = f[1];
      for (int j = i & 1 ? 1 : 2; j <= k; j += 2) f[j] = f[j - 1] + f[j + 1];
    } else {
      cnt++;
      for (int j = ((k & 1) == (i & 1)) ? k : k - 1; j >= 1; j--)
        f[j] = f[j - 1];
      f[0] = 0;
    }
  }
  int a = f[0];
  cnt = k - cnt;
  while (cnt-- > 0) a *= 25;
  printf("%u", a);
  return 0;
}
