#include<iostream>
#include<cstdio>
using namespace std;
int q;
int f(int y){
	int p=1;
	int x=y;
	while(x){
		x&=x-1;
		p<<=1;
	}
	return p;
}
int main(){
	//freopen("ex_number3.in","r",stdin);
	
	scanf("%d",&q);
	for(int i=1;i<=q;i++){
		int l,r;
		int t=0;
		scanf("%d%d",&l,&r);
		for(int j=l;j<=r;j++){
			int k=f(j);
			if(j%k==0&&(j/k)%2==1){
				printf("%d\n",j);
				t=1;
				break;
			}
		}
		if(!t)printf("%d\n",-1);
	}

	return 0;
}