#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  vector<int> a(n);
  int maxx = 0;
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
    maxx = max(maxx, a[i]);
  }
  cout << max(0, maxx - 25) << "\n";
}
