#include<bits/stdc++.h>
#define int long long
using namespace std;
inline int read(){
    int x=0,f=1;char c=getchar();
    while(c<'0'||c>'9'){if(c=='-')f=-f;c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
    return x*f; 
}
map<int,int>mp;
int n,k,ans;
signed main(){
	freopen("in.txt","r",stdin);
	freopen("out.txt","w",stdout);
	n=read(),k=read();
	for(int i=1;i<=n;i++){
		int x=read();
		for(int j=1;j*j<=x;j++){
			if(x%j)continue;
			mp[j]++;
			if(j*j!=x)mp[x/j]++;
		}
	}
	for(auto i:mp){
		if(mp[i.second]>=k)ans=max(ans,i.first);
	}
	printf("%lld\n",ans);
    return 0;
}