#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10, mod = 1e9 + 7;
const long long inf = 1e18;
unsigned int dp[maxn];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie();
  int n, cnt = 0;
  cin >> n;
  string s;
  cin >> s;
  if (n & 1) return cout << 0 << endl, 0;
  dp[0] = 1;
  for (int i = 0; i < n; i++) {
    if (s[i] != '?') {
      cnt++;
      for (int j = i + 1; j >= 0; j -= 2) dp[j] = (j == 0 ? 0 : dp[j - 1]);
    } else {
      for (int j = i + 1; j >= 0; j -= 2)
        dp[j] = dp[j + 1] + (j == 0 ? 0 : dp[j - 1]);
    }
  }
  int num = (n - 2 * cnt) / 2;
  unsigned int ans = dp[0];
  for (int i = 0; i < num; i++) ans *= 25;
  return cout << ans << endl, 0;
}
