a,b=map(int,input().split())
n=0
if b==0:
    print(1)
elif a==1:
    if n%b==0 and n//b>0:
        print(n//b)
else:
    for i in range(10**5):
        n=a*n+b
        if n==0:
            print(i+1)
            break
    else:
        print(-1)