require'prime'
n,k=gets.split.map &:to_i
r=t=0
o=Hash[n.prime_division]
(2...n).each{|i|
	q=i.prime_division
	l=0
	q.each{|n,p|l+=[o[n].to_i,p].min}
	if l>=k
		s=q.map{|n,p|p+1}.reduce(:*)
		if r<s
			r=s
			t=i
		end
	end
}
p t