T = data[0]
index = 1

for _ in range(T):
    N = data[index]
    M = data[index + 1]
    index += 2

    left = 0
    right = N // 4

    while left <= right:
        mid = (left + right) // 2
        need_stick = mid * 2
        shortage = max(0, need_stick - M)
        convert = (shortage + 3) // 4
        need_wood = mid * 4 + convert * 2

        if need_wood <= N:
            left = mid + 1
        else:
            right = mid - 1

    answer = right * 3
    print(answer)