def make_divisors(n):
    lower_divisors , upper_divisors = [], []
    i = 1
    while i*i <= n:
        if n % i == 0:
            lower_divisors.append(i)
            if i != n // i:
                upper_divisors.append(n//i)
        i += 1
    return lower_divisors + upper_divisors[::-1]

T=int(input())
for _ in range(T):
    N,K=map(int,input().split())
    if N>K*K:
        print(N)
        continue
    if N<=K:
        print(-1)
        continue
    for i in range(N,K,-1):
        div = make_divisors(i)
        f = True
        for d in div:
            if d<=K and i//d<=K:
                f = False
                break
        if f:
            print(i)
            break
    if not f:
        print(-1)