#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e5 + 55;
const int inf = 1e9 + 77;
const int MOD = 1e9 + 7;
const double PI = 3.14159265359;
const double eps = 1e-7;
int main() {
  int x;
  scanf("%d", &x);
  for (int a = 1; a <= x; ++a) {
    for (int b = 1; b <= x; ++b) {
      if (a % b == 0 && a * b > x && a / b < x) {
        cout << a << ' ' << b;
        return 0;
      }
    }
  }
  cout << -1;
  return 0;
}
