#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> a;
  for (int i = 0; i < n; ++i) {
    int tmp;
    cin >> tmp;
    a.push_back(tmp);
  }
  sort(a.begin(), a.end());
  if (a[n - 1] > 25)
    cout << a[n - 1] - 25;
  else
    cout << 0;
}
