#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int sum = 0;
  while (n--) {
    int x;
    cin >> x;
    sum = max(sum, x);
  }
  if (sum < 25) {
    cout << 0;
    return 0;
  } else {
    cout << sum - 25;
  }
}
