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