#イライラするわホンマに

def is_good(x, K):
    import math
    for a in range(1, int(math.isqrt(x)) + 1):
        if x % a == 0:
            b = x // a
            if a <= K and b <= K:
                return False
    return True

def solve(N, K):
    if N <= K:
        return -1
    if N > K * K:
        return N
    for x in range(N, K, -1):
        if is_good(x, K):
            return x
    return -1

T=int(input())
for i in range(T):
    N, K = (int(x) for x in input().split())
    print(solve(N, K))