import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop, core.stdc.string;

void main() {
    auto X = readln.chomp.to!long;

    foreach (a; 1..X+1) {
        foreach (b; 1..X+1) {
            if (a % b == 0 && a * b > X && a < b * X) {
                writeln(a, " ", b);
                return;
            }
        }
    }

    writeln(-1);
}
