def solve():
    N, M = [int(s) for s in input().split()]

    ans = 0

    fence = min(N // 4, M // 2)
    ans += fence * 3

    N -= 4 * fence
    M -= 2 * fence

    ok, ng = 0, 10**9
    while abs(ok - ng) > 1:
        mid = (ok + ng) // 2

        stick = ((mid * 2 + 3) // 4) * 2
        wood = 4 * mid

        if stick + wood <= N:
            ok = mid
        else:
            ng = mid

    ans += ok * 3
    print(ans)


if __name__ == "__main__":
    T = int(input())

    for _ in range(T):
        solve()