#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int arr[n];
  for (int i = 0; i < n; i++) cin >> arr[i];
  sort(arr, arr + n);
  if (arr[n - 1] > 25) {
    int ans = arr[n - 1] - 25;
    cout << ans;
    return 0;
  }
  cout << 0;
  return 0;
}
