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