from math import gcd

n = int(input())
m = int(input())

g = gcd(n, m)
n //= g
m //= g

num2 = 0
num5 = 0
while m % 2 == 0:
    m //= 2
    num2 += 1
while m % 5 == 0:
    m //= 5
    num5 += 1

if m > 1:
    print(-1)
    exit()

while n % 10 == 0:
    n //= 10

n %= 10
while num5 < num2:
    n *= 5
    n %= 10
    num5 += 1
while num2 < num5:
    n *= 2
    n %= 10
    num2 += 1

print(n)