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