#include <bits/stdc++.h>
using namespace std;
int main() {
  int k;
  cin >> k;
  int maks = 0;
  for (int tmp = 0; tmp < k; tmp++) {
    int a;
    cin >> a;
    if (a > 25) {
      maks = max(maks, a - 25);
    }
  }
  cout << maks << "\n";
}
