import math
import sys
N = int(input())
M = int(input())
gcd = math.gcd(N,M)
N1 = N//gcd
M1 = M//gcd
l2 = 0
while M1 % 2 == 0:
    l2 += 1
    M1 //= 2
l5 = 0
while M1 % 5 == 0:
    l5 += 1
    M1 //= 5
if M1 != 1:
    print(-1)
    sys.exit()
if l2 > l5:
    print(5)
elif l2 == l5:
    div = 10
    while N1%div == 0:
        N1 //= 10
    print(N1)
else:
    c5 = l5-l2
    while c5:
        N1 %= 5
        N1 *= 2
        c5 -= 1
    print(N1)