import sys
input = sys.stdin.buffer.readline

table_len = 5000005
table = [True] * table_len
for i in range(2, table_len):
    if table[i]:
        for j in range(2*i, table_len, i):
            table[j] = False

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