#include <bits/stdc++.h>
using namespace std;

typedef unsigned int ui;

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int n;
	int k;
	cin>>n>>k;
	vector<ui> M(n);
	vector<bool> killed(n,false);
	for(auto &x:M){
		cin>>x;
	}
	ui result=0;
	for(ui mask=1u<<30;mask !=0;mask >>=1) {
		int count=0;
		for (int i=0;i<n;i++){
			if((!killed[i])&&(mask & M[i])){
				count++;
			}
		}
		if(count>=k){
			result|=mask;
			for (int i=0;i<n;i++){
				if((mask & M[i])==0){
					killed[i]=true;
				}
			}				
		}
	}
	cout <<result<<endl;
}