#include<iostream>
#include<queue>
#define int long long
using namespace std;
priority_queue<int,vector<int>,greater<int> >pq;
int n,k,a[100005],hd;
main(){
	ios::sync_with_stdio(0);
	cin>>n>>k;
	for(register int i=1;i<=n;++i)cin>>a[i],pq.push(a[i]);
	for(register int i=1;i<=k;++i){
		while(hd==pq.top())pq.pop();
		hd=pq.top(),pq.pop();
		for(register int j=1;j<=n;++j)pq.push(a[j]*hd);
	}
	cout<<hd;
	return 0;
}