#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  int n;
  cin >> n;
  int a[n];
  for (int i = 0, _ = n; i < _; i++) cin >> a[i];
  sort(a, a + n);
  int save = 25 - n;
  long long ans = 0;
  int j = 0;
  for (int i = 1, _ = a[n - 1]; i < _; i++) {
    if (a[j] != i) {
      if (save > 0)
        save--;
      else
        ans++;
    }
    if (a[j] == i) j++;
  }
  cout << ans;
  return 0;
}
