T = int(input())

def is_ok(n):
    capn = n * 4
    capm = n * 4
    if capn < N:
        return False
    capn -= N
    capm += capn
    return capm >= M

def binary_search(ok, ng):
    while abs(ok-ng) > 1:
        mid = (ok+ng) // 2
        if is_ok(mid):
            ok = mid
        else:
            ng = mid
    return ok

for _ in range(T):
    N, M = map(int, input().split())
    ans = binary_search(5*10**8, 0)
    print(ans)