#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, max, i;
  cin >> n;
  int arr[n];
  for (i = 0; i < n; i++) cin >> arr[i];
  max = *max_element(arr, arr + n);
  if (max > 25)
    cout << max - 25 << endl;
  else
    cout << "0" << endl;
  return 0;
}
