#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  for (; !isdigit(ch); ch = getchar())
    if (ch == '-') f = -1;
  for (; isdigit(ch); ch = getchar()) x = x * 10 + ch - '0';
  return x * f;
}
char s[100005];
unsigned int f[100005];
int main() {
  int n = read();
  if (n & 1) {
    cout << 0;
    return 0;
  }
  scanf("%s", s + 1);
  int cnt = 0;
  f[0] = 1;
  for (int i = 1; i <= n; ++i) {
    if (s[i] == '?')
      for (int j = (i >> 1); j && j >= (i - n / 2); --j) f[j] += f[j - 1];
    else
      cnt++;
  }
  unsigned int ans = f[n / 2];
  for (int i = 1; i <= (n / 2 - cnt); ++i) ans = ans * 25;
  cout << ans;
  return 0;
}
