#include <bits/stdc++.h>
using namespace std;
const long long mod = 4294967296;
char s[100010];
unsigned int dp[100010];
int n;
int main() {
  scanf("%d %s", &n, s);
  int cnt = 0;
  for (int i = 0; i < n; i++)
    if (s[i] == '?') cnt++;
  if (n % 2 == 1 || cnt * 2 < n) {
    printf("0\n");
    return 0;
  }
  memset(dp, 0, sizeof(dp));
  dp[0] = 1;
  for (int i = 0; i < n; i++) {
    int mmin = max(0, i + 1 - n / 2), mmax = (i + 1) / 2;
    if (s[i] == '?') {
      for (int j = mmax; j >= mmin && j >= 1; j--)
        dp[j] += dp[j - 1], dp[j] %= mod;
    }
  }
  unsigned int ret = dp[n / 2] % mod;
  for (int i = 0; i < cnt - n / 2; i++) ret *= 25, ret %= mod;
  cout << ret << endl;
  return 0;
}
