#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100000 + 10;
char str[MAXN];
int n;
unsigned int f[MAXN];
int main() {
  cin >> n;
  if (n & 1) puts("0"), exit(0);
  scanf("%s", str + 1);
  f[0] = 1;
  for (int i = 1; i <= n; ++i)
    for (int j = i & 1; j <= i; j += 2)
      f[j] = (j ? f[j - 1] : 0) + (str[i] == '?' ? f[j + 1] : 0);
  unsigned int CC = f[0];
  int cnt = n / 2;
  for (int i = 1; i <= n; ++i) cnt -= (str[i] != '?');
  if (cnt < 0) puts("0"), exit(0);
  while (cnt) CC *= 25, --cnt;
  cout << CC << endl;
  fclose(stdin);
  fclose(stdout);
  return 0;
}
