#include<stdio.h>
void solve()
{
	long long int l, r;
	scanf("%lld %lld", &l, &r);
	long long int a, b;
	for (b = 1; b <= r; b *= 2);
	b /= 2;
	a = b - 1;
	if (a < l)
	{
		if (l == 0)
			printf("0\n");
		else
			printf("-1\n");
	}
	else
		printf("%lld\n", a * b);
	return;
}
int main()
{
	int t;
	scanf("%d", &t);
	for (; t > 0; t--)
		solve();
	return 0;
}