N = 5 * 10 ** 6
prime = [True] * (N + 1)
prime[0] = prime[1] = False
for i in range(2, N + 1):
    if prime[i]:
        for j in range(2 * i, N + 1, i):
            prime[j] = False

for _ in range(int(input())):
    A, P = map(int, input().split())
    if prime[P]:
        print(1)
    else:
        print(-1)