#include <bits/stdc++.h>
using namespace std;
char str[110000];
unsigned int cnt[110000];
unsigned int Pow(unsigned int x, unsigned int y) {
  if (y == 0) return 1;
  unsigned int res = Pow(x, y / 2);
  res = res * res;
  if (y % 2) res = res * x;
  return res;
}
int main() {
  int N, i, j, maxv, a1, a2, que;
  unsigned int ans;
  scanf("%d", &N);
  scanf("%s", str);
  if (N & 1) {
    puts("0");
    return 0;
  }
  cnt[0] = 1;
  for (i = 0; i < N; i++) {
    if (str[i] == '?') {
      maxv = min(i + 2, N - i);
      a2 = 0;
      for (j = 0; j < maxv; j++) {
        a1 = cnt[j];
        cnt[j] = a2 + cnt[j + 1];
        a2 = a1;
      }
    } else {
      maxv = min(i + 1, N - i + 1);
      for (j = maxv; j > 0; j--) cnt[j] = cnt[j - 1];
      cnt[0] = 0;
    }
  }
  que = 0;
  for (i = 0; i < N; i++)
    if (str[i] == '?')
      que++;
    else
      que--;
  ans = cnt[0] * Pow(25, que / 2);
  printf("%u\n", ans);
  return 0;
}
