from sys import stdin
input = stdin.readline

for _ in range(int(input())):
    N, M = map(int, input().split())

    left = -1
    right = N//2+1
    while left+1 < right:
        mid = (left+right)//2
        if M+4*mid <= N-2*mid//2:
            left = mid
        else:
            right = mid
    
    ans = 0
    for i in range(left-10, left+10):
        if i < 0: continue
        if N < 2*i: continue
        a, b = N-2*i, M+4*i
        ans = max(ans, min(a//4, b//2))
    
    print(ans*3)