#include <bits/stdc++.h>
using namespace std;
int main() {
  int K;
  int m = -1;
  cin >> K;
  while (K--) {
    int x;
    cin >> x;
    m = max(m, x);
  }
  if (m <= 25) m = 25;
  cout << m - 25 << endl;
  return 0;
}
