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