n, m = $<.map(&:to_i)
g = n.gcd(m)
n /= g
m /= g
if m != 1
    cnt = [0,0]
    while m % 2 == 0
        cnt[0] += 1
        m /= 2
    end
    while m % 5 == 0
        cnt[1] += 1
        m /= 5
    end
    if m != 1
        p -1
        exit
    end
    if cnt[0] > cnt[1]
        n *= 5 ** (cnt[0] - cnt[1])
    else 
        n *= 2 ** (cnt[1] - cnt[0])
    end
end
s = n.to_s.reverse
s.size.times do |i|
    next if s[i] == ?0
    puts s[i]
    break
end