#include <bits/stdc++.h>
using namespace std;
const int maxn = 1000000 + 10;
const int INF = 1e9 + 7;
const int MOD = 1e9 + 7;
const double eps = 1e-10;
const double pi = acos(-1);
int T, cases, n, m;
int main() {
  ios::sync_with_stdio(false);
  ;
  cin >> n;
  for (int a = 1; a <= n; a++)
    for (int b = 1; b <= n; b++) {
      if (a % b == 0 && a * b > n && a < b * n) {
        cout << a << " " << b << endl;
        return 0;
      }
    }
  cout << "-1" << endl;
  return 0;
}
