import sys


def input(): return sys.stdin.readline().rstrip()


def isok(x, k):
    i = 2
    while i*i <= x and i <= k:
        if x % i == 0 and x // i <= k:
            return False
        i += 1
    return True


def main():
    t = int(input())
    for _ in range(t):
        n, k = map(int, input().split())
        for i in range(n, k, -1):
            if isok(i, k):
                print(i)
                break
        else:
            print(-1)


if __name__ == "__main__":
    main()