#include <bits/stdc++.h>
using namespace std;
bool arr[1000009];
int main() {
  int k;
  cin >> k;
  vector<int> a(k);
  int be = 1;
  int cou = 0;
  for (int i = 0; i < k; i++) {
    cin >> a[i];
    arr[a[i]] = true;
  }
  sort(a.begin(), a.end());
  if (a[a.size() - 1] > 25) {
    cout << a[a.size() - 1] - 25;
  } else
    cout << 0;
}
