#include <bits/stdc++.h>
using namespace std;
int TN = 1;
void solve() {
  int n;
  cin >> n;
  for (int i = 1; i <= 100; i++) {
    for (int j = 1; j <= 100; j++) {
      if (i % j == 0 && i * j > n && i / j < n) {
        cout << i << " " << j;
        return;
      }
    }
  }
  cout << -1;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  while (TN--) solve();
  return 0;
}
