n = gets.to_i
m = gets.to_i
a = Array.new(2, 0)
g = n.gcd(m)
n /= g
m /= g
tm = m
while tm % 2 == 0 || tm % 5 == 0 do
    if tm % 2 == 0
        tm /= 2
        a[0] += 1
    end
    if tm % 5 == 0
        tm /= 5
        a[1] += 1
    end
end
if tm != 1
    puts -1
    exit
end
b = (a[0] > a[1]) ? a[0] : a[1];
r = (10 ** b) / m
s = (r * n).to_s
(s.length - 1).downto(0) do |i|
    if s[i].to_i != 0
        puts s[i]
        break
    end
end