#include <bits/stdc++.h>
using namespace std;
int main() {
  long long x;
  while (cin >> x) {
    long long i, a, b, arr[10005];
    for (i = 1; i <= x; i++) {
      arr[i] = i;
    }
    for (a = 1; a <= x; a++) {
      for (b = 1; b <= x; b++) {
        if (a % b == 0 && a * b > x && a / b < x) {
          cout << a << " " << b << endl;
          return 0;
        }
      }
    }
    cout << "-1" << endl;
  }
  return 0;
}
