from collections import defaultdict
from math import gcd, sqrt
def Fraction(A, B):
    G = gcd(A, B)
    return A // G, B // G

def PrimeFactorization(N):
    ret = defaultdict(int)
    for i in range(2,int(sqrt(N))+1):
        while N % i == 0:
            ret[i] += 1
            N //= i
    if N > 1:
        ret[N] += 1
    return ret

mod = 10**10
N = int(input())
M = int(input())
N,M = Fraction(N, M)
P = PrimeFactorization(M)
for i in P.keys():
    if i != 2 and i != 5:
        print(-1)
        exit()
N *= pow(5, max(0, P[2]-P[5]))
N *= pow(2, max(0, P[5]-P[2]))
N %= mod
while N % 10 == 0:
    N //= 10
print(N % 10)