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