#include <bits/stdc++.h>
using namespace std;
int n, a[10005], i, maxim;
int main() {
  cin >> n;
  for (i = 1; i <= n; i++) cin >> a[i];
  maxim = a[1];
  for (i = 2; i <= n; i++)
    if (a[i] > maxim) maxim = a[i];
  if (maxim > 25)
    cout << maxim - 25;
  else
    cout << '0';
}
