#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:66777216")
using namespace std;
const int N = 100007;
unsigned int dp[N];
char st[N];
int n;
int main() {
  scanf("%d%s", &n, st);
  dp[0] = 1;
  unsigned int coef = 25;
  for (int i = 1; i <= n; ++i) {
    int i1 = i - 1;
    for (int j = i % 2 + 2; j <= i; j += 2) {
      dp[j] = 0;
      if (st[i1] == '?') {
        dp[j] = dp[j + 1] + coef * dp[j - 1];
      } else {
        dp[j] = dp[j - 1];
      }
    }
    if (i % 2 == 0) {
      if (st[i1] == '?') {
        dp[0] = dp[1];
      } else {
        dp[0] = 0;
      }
    } else {
      if (st[i1] == '?') {
        dp[1] = dp[2] + 25 * dp[0];
      } else {
        dp[1] = dp[0];
      }
    }
  }
  cout << ((n & 1) ? 0 : dp[0]) << endl;
  return 0;
}
