#include<bits/stdc++.h>
using namespace std;
#define VI vector<int>
#define PII pair<int, int>
#define VPI vector<PII>
#define mp make_pair
#define eb emplace_back
#define pb push_back
#define st first
#define nd second
#define endl '\n'
#define debug(x) cerr << #x << " " << x << endl;
#define ll long long

#define int ll

const int N = 1e6 + 7;
int n, k, t[N];

int test(int ile) {
	int ret = 0;
	for(int i = 0; i < n; i++) {
		if((t[i] & ile) == ile) ret ++;
	}
	//debug(ile);
	//debug(ret);
	return ret;
}

void solve() {
	cin >> n >> k;
	for(int i = 0; i < n; i++) {
		cin >> t[i];
	}
	
	int ans = 0;
	for(int i = 31; i >= 0; i--) {
		//debug(k);
		if(test(ans + (1ll << i)) >= k) {
			//debug("huj");
			ans += (1ll << i);
		}
	}
	
	cout << ans << endl;
}

int32_t main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	int test = 1;
	
	while(test--){
		solve();
	}
	
	return 0;
}