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