#include <bits/stdc++.h>
using namespace std;
int a[30];
int main() {
  int n, i, x;
  cin >> n;
  for (i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  x = a[n - 1] - 25;
  if (x <= 0) x = 0;
  cout << x;
  return 0;
}
