#include <bits/stdc++.h>
using namespace std;
int n, m, z, x, y, o, w;
unsigned int f[2][100005];
char s[100005];
int main() {
  scanf("%d\n", &n);
  scanf("%s", s + 1);
  f[0][0] = 1;
  for (int i = 1; i <= n; ++i) {
    o = i & 1;
    w = (i + 1) & 1;
    x = min(i, n - i);
    if (o == 0)
      y = 2;
    else
      y = 1;
    if (s[i] == '?') {
      f[o][0] = f[w][1];
      for (int j = y; j <= x; j += 2) f[o][j] = f[w][j - 1] * 25 + f[w][j + 1];
    } else {
      f[o][0] = 0;
      for (int j = y; j <= x; j += 2) f[o][j] = f[w][j - 1];
    }
  }
  o = n & 1;
  printf("%u", f[o][0]);
  return 0;
}
