#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000000000000

int main(){

	int N,K;
	cin>>N>>K;
	
	vector<int> cnt(N+1,0);
	
	for(int i=1;i<N;i++){
		for(int j=i;j<N;j+=i)cnt[j] ++;
	}
	
	int n = N;
	vector<int> p;
	for(int i=2;i<=n;i++){
		while(n%i==0){
			p.push_back(i);
			n/=i;
		}
	}
	int maxi = 0;
	int ans = 0;
	
	set<int> S;
	rep(i,(1<<p.size())){
		int now = 1;
		int c = 0;
		rep(j,p.size()){
			if((i>>j)&1){
				c++;
				now *= p[j];
			}
		}
		if(c<K)continue;
		if(S.count(now))continue;
		S.insert(now);
		
		for(int j=now;j<N;j+=now){
			if(maxi<cnt[j]){
				maxi = cnt[j];
				ans = j;
			}
			else if(maxi==cnt[j]){
				ans = min(ans,j);
			}
		}
	}
	
	cout<<ans<<endl;
	
	return 0;
}