#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
using namespace std;
unsigned int dp[50010];
int n;
char s[100010];
int main() {
  scanf("%d%s", &n, s + 1);
  if (n & 1) {
    puts("0");
    return 0;
  }
  dp[0] = 1;
  int sum = 0;
  for (int i = 1; i <= n; i++) {
    if (s[i] == '?')
      for (int j = (i >> 1); j >= 1; j--) dp[j] += dp[j - 1];
    else
      sum++;
  }
  unsigned int ans = dp[n / 2];
  for (int i = 0; i < (n - 2 * sum) / 2; i++) ans *= 25;
  printf("%u\n", ans);
  return 0;
}
