import math
N = int(input())
M = int(input())
N *= 10 ** 100
G = math.gcd(N, M)
N //= G
M //= G
if M != 1:
    print(-1)
else:
    ANS = ""
    for C in str(N):
        if C != "0":
            ANS = C
    print(ANS)