T = int(input())
for _ in range(T):
    L,R = list(map(int,input().split()))
    a = R >> (R.bit_length() - 1) << (R.bit_length() - 1)
    b = a - 1
    assert a & b == 0
    print(a * b if L <= a <= R and L <= b <= R else -1)