#include <bits/stdc++.h>
using namespace std;
int main() {
  int k, a = 0;
  cin >> k;
  for (int i = 1; i <= k; i++) {
    int v;
    cin >> v;
    a = max(a, v);
  }
  if (a <= 25)
    cout << 0 << endl;
  else
    cout << (a - 25) << endl;
}
