import sys

def main():
    data = sys.stdin.buffer.read().split()
    t = int(data[0])
    out = []
    idx = 1
    for _ in range(t):
        L = int(data[idx]); R = int(data[idx + 1]); idx += 2
        if R == 0:
            out.append(0)
            continue
        k = R.bit_length() - 1
        hi = 1 << k
        if L >= hi:
            out.append(-1)
        else:
            out.append(hi * (hi - 1))
    sys.stdout.write("\n".join(map(str, out)) + "\n")

main()