题解 | 构造数对

经过研究发现，b=1不行，那么我们就选取b=2，然后基于b去寻找符合条件的a

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner=new Scanner(System.in);
		int x=scanner.nextInt();
		int b=2;
		for (int a = 2; a < 2*x; a+=2) {
			if(a>x/b) {
				System.out.println(a+" "+b);
				return;
			}
		}
		System.out.println("-1");

	}

}