#include <bits/stdc++.h>
using namespace std;
int main() {
  int k;
  cin >> k;
  int max = 0;
  for (int i = 0; i < k; i++) {
    int x;
    cin >> x;
    if (max < x) {
      max = x;
    }
  }
  if (max - 25 > 0)
    cout << max - 25;
  else
    cout << "0";
}
