#include <bits/stdc++.h>
using namespace std;
namespace WorkSpace {
const int max_num = 100010;
unsigned int F[max_num >> 1];
void Main() {
  register int N;
  scanf("%d", &N);
  if (N & 1) {
    printf("0\n");
    return;
  }
  static char S[max_num];
  register int Half = N >> 1;
  scanf("%s", S + 1);
  F[0] = 1;
  register int Num = 0;
  for (register int i = 1; i <= N; ++i) {
    if (S[i] == '?') {
      for (register int j = i >> 1; j && j >= i - Half; --j) F[j] += F[j - 1];
    } else
      ++Num;
  }
  register unsigned int ans = F[Half];
  for (register int i = 0; i < Half - Num; ++i) ans *= 25;
  printf("%u\n", ans);
}
}  // namespace WorkSpace
int main() {
  WorkSpace ::Main();
  return 0;
}
