A,B = map(int,input().split())
N = 0
N_list = []
i = 0
flg = False

if A > 0 and B > 0:
    print(-1)
elif A == B :
    print(-1)
    
else:
    while flg == False:
        N = A*N +B
        if N in N_list:
            break
        N_list.append(N)
        i += 1
        if N == 0:
            print(i)
            flg = True
            break
    
    if flg == False:
        print(-1)