for _ in range(int(input())):
    n, m = map(int, input().split())
    def f(x):
        if n < 4*x: return False
        return (n - 4*x) // 2 * 4 + m >= 2*x
    l = 0
    r = 1
    while f(r): l, r = r, r * 2
    while r - l > 1:
        c = (l + r) // 2
        if f(c): l = c
        else: r = c
    print(3*l)