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