package no3642;
import java.util.*;
public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
		StringBuilder sb = new StringBuilder();
		while(t > 0) {
			t--;
			int l = sc.nextInt();
			int r = sc.nextInt();
			if(r == 0) {
				sb.append(0  +"\n");
				continue;
			}
			long v = 1;
			while(v * 2L <= r) {
				v *= 2L;
			}if((l & v) != 0) {
				sb.append(-1 + "\n");
				continue;
			}sb.append((long)v * (long)(v - 1) + "\n");
		}System.out.print(sb);
	}

}