T = int(input())

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

    if N <= (M // 2) * 4:
        ans = (N // 4) * 3
        print(ans)

    else:
        t1, M = divmod(M, 2)
        N -= t1 * 4
   
        ok = 0
        ng = 10 ** 9
        while ng - ok > 1:
            m = (ok +ng) // 2
            if m * 4 > N:
                ng = m
                continue
            nn = N - m * 4
            if (nn//2) * 4 + M >= m * 2:
                ok = m
            else:
                ng = m
        
        ans = (t1+ok)  * 3
        print(ans)