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