#include<bits/stdc++.h>
#include <atcoder/all>
#ifdef LOCAL
#include <debug_print.hpp>
#define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (static_cast<void>(0))
#endif
using namespace atcoder;
using mint=modint1000000007;
using namespace std;
using ll=long long;
using ul=unsigned long long;
int dx[9] = {-1, 1, 0, 0, -1, -1, 1, 1, 0};
int dy[9] = {0, 0, -1, 1, -1, 1, -1, 1, 0};
using Graph=vector<vector<int>>;
ll op(ll a,ll b){return min(a,b);}
ll e(){return 2e9;}
vector<pair<long long,int>>prime(long long N){
	vector<pair<long long,int>>ans;
	for(long long i=2;i*i<=N;i++){
		int cnt=0;
		while(N%i==0)cnt++,N/=i;
		ans.push_back({i,cnt});
	}
	if(N!=1)ans.push_back({N,1});
	return ans;
}
int main(){
	int M=0,m;
	int N,K;
	cin>>N>>K;
	vector<pair<ll,int>>A=prime(N);
	map<int,int>mp;
	for(auto[a,b]:A)mp[a]=b;
	for(int i=2;i<N;i++){
		vector<pair<ll,int>>B=prime(i);
		map<int,int>mp2;
		for(auto[a,b]:B)mp2[a]=b;
		int cnt=0;
		for(auto[k,v]:mp)cnt+=min(v,mp2[k]);
		int ans=1;
		if(cnt>=K){
			for(auto[a,b]:B)ans*=(b+1);
			if(M<ans)m=i,M=ans;
		}
	}
	cout<<m<<endl;
}