#include <bits/stdc++.h>
using namespace std;
int aa[30];
int main() {
  int n;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", &aa[i]);
  sort(aa, aa + n);
  printf("%d", max(0, aa[n - 1] - 25));
  return 0;
}
