#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 100;
int read() {
  int s = 0, f = 0;
  char ch = getchar();
  while (!isdigit(ch)) f |= (ch == '-'), ch = getchar();
  while (isdigit(ch)) s = s * 10 + (ch ^ 48), ch = getchar();
  return f ? -s : s;
}
char s[N];
int cntp;
unsigned int dp[N], ans = 1;
signed main() {
  int n = read();
  if (n & 1) {
    printf("0");
    return 0;
  } else {
    int mid = n >> 1;
    dp[0] = 1;
    scanf("%s", s + 1);
    for (int i = 1; i <= n; i++) {
      if (s[i] == '?')
        for (int j = i >> 1; j >= i - mid && j; j--) dp[j] += dp[j - 1];
      else
        cntp++;
    }
    for (int i = 1; i <= mid - cntp; i++) ans = ans * 25;
    cout << ans * dp[mid];
  }
  return 0;
}
