def main():
    def f(a, b):
        return min(a//4, b//2)
    n, m = list(map(int, input().split()))
    ans = min(n//4, m//2)
    n -= ans*4
    m -= ans*2
    if 4 <= n:
        l = 0
        r = n // 4
        while r - l > 1:
            mi = (l+r) >> 1
            if f(n-mi*2, m+mi*4) < f(n-(mi+1)*2, m+(mi+1)*4):
                l = mi+1
            else:
                r = mi
        ans += max(f(n-l*2, m+l*4), f(n-r*2, m+r*4))
    return 3 * ans

for _ in range(int(input())):
    print(main())