#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  long long x;
  cin >> x;
  for (long long i = 1; i <= x; i++) {
    for (long long j = i; j <= x; j++) {
      if (j % i == 0 && i * j > x && j / i < x) {
        cout << j << ' ' << i << endl;
        return 0;
      }
    }
  }
  cout << -1 << endl;
}
