def solve():
	N, M = map(int, input().split())
	l, r = 0, N+M
	while l < r:
		m = l + (r - l) // 2
		if M <= 4*m and N <= 8*m - M:
			r = m
		else:
			l = m + 1
	print(l)

T = int(input())
for t in range(T):
	solve()