#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int arr = 0, temp;
  for (int i = 0; i < n; ++i) {
    cin >> temp;
    if (temp > arr) arr = temp;
  }
  int ans = arr - 25;
  cout << (ans > 0 ? ans : 0) << endl;
  return 0;
}
