def main():
    import sys
    input = sys.stdin.readline

    p=[True]*5000001
    p[0]=p[1]=False
    i=2
    ps=[]
    while i<5000000:
        if p[i]:
            ps.append(i)
            j=i<<1
            while j<=5000000:
                p[j]=False
                j+=i
        i+=1
    
    for _ in range(int(input())):
        a,b=map(int,input().split())
        if p[b]:
            print(pow(a%b,b-1,b))
        else:
            print(-1)
if __name__=='__main__':
    main()