#include<iostream>
#include<cstdio>
#include<algorithm>
#include<set>
#include<vector>
#include<queue>
using namespace std;
int n,k;
int ss[100000+10]; 
int main(){
	freopen("humble.in","r",stdin);
	freopen("humble.out","w",stdout);
	cin>>n>>k;
	for(int i=1;i<=n;i++){
		cin>>ss[i];
	}
	sort(ss+1,ss+n+1);
	priority_queue<int,vector<int>,greater<int> >pq;
	set<int>s;
	pq.push(1);
	s.insert(1);
	for(int i=1;;i++){
		int x=pq.top();
		pq.pop() ;
		if(i==k){
			cout<<x;
			break;
		}
		for(int j=1;j<=n;j++){
			int x2=x*ss[j];
			if(!s.count(x2)){
			   s.insert(x2);
			   pq.push(x2);  
			}
		}
	}
	fclose(stdin);
	fclose(stdout);
	return 0;
}