/* -*- coding: utf-8 -*-
 *
 * 3624.cc:  No.3624 Product - yukicoder
 */

#include<cstdio>
#include<algorithm>

using namespace std;

/* constant */

/* typedef */

using ui = unsigned int;
using ull = unsigned long long;

/* global variables */

/* subroutines */

/* main */

int main() {
  int tn;
  scanf("%d", &tn);

  while (tn--) {
    ui l, r;
    scanf("%u%u", &l, &r);

    ui b = 1;
    while ((b << 1) <= r) b <<= 1;
    ui a = b - 1;
    
    if (l <= a) printf("%llu\n", (ull)a * b);
    else puts("-1");
  }

  return 0;
}