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