#include <bits/stdc++.h>
using namespace std;
using DO = double;
using INT = long long;
using pii = pair<int, int>;
using pi3 = pair<pii, int>;
int power(int a, int b, int mod, int ans = 1) {
  for (; b; b >>= 1, a = 1LL * a * a % mod)
    if (b & 1) ans = 1LL * ans * a % mod;
  return ans;
}
int main() {
  int n;
  cin >> n;
  for (int a = 1; a <= 10000; a++)
    for (int b = 1; b <= 10000; b++)
      if (a % b == 0 and a / b < n and a * b > n) {
        cout << a << ' ' << b << endl;
        return 0;
      }
  cout << -1 << endl;
  return 0;
}
