T=int(input())
A,P=0,0
PR=[1]*6000000
PR[0]=0
PR[1]=0
for i in range(2,6000000):
  if PR[i]:
    for j in range(i*2,6000000,i):
      PR[j]=0
for i in range(T):
  A,P=map(int,input().split())
  if PR[P]:
    print(1)
  else:
    print(-1)