#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  int n, tmp, ans = 0, mx = -1;
  cin >> n;
  for (int i = 0; i < n && cin >> tmp; ++i) mx = max(tmp, mx);
  cout << (mx > 25 ? mx - 25 : 0);
}
