# -*- coding: utf-8 -*
import math
n = int(input())
m = int(input())

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

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

lieSolution = 0
while m % 5 == 0:
    m //= 5
    n *= 2
    n %= 10
while m % 2 == 0:
    m //= 2
    n *= 5
    n %= 10
    if n == 0:
        lieSolution += 1

if m == 1:
    if lieSolution == 0:
        print(n)
    else:
        print(lieSolution)
else:
    print(-1)