#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int maxVal = -1e9;
  for (int i = 0; i < n; i++) {
    int val;
    cin >> val;
    maxVal = max(maxVal, val);
  }
  cout << max(maxVal - 25, 0);
  return 0;
}
