#include <iostream>

using namespace std;

const int MAXN = 2<<17;

int arr[MAXN];
bool dead[MAXN];

int main() {
	int n, k;
	int sol = 0;

	cin>>n>>k;
	
	for (int i = 0; i < n; ++i)
		cin>>arr[i];
	
	for (int j = 29; j >= 0; --j) {
		int num = 0;
		for (int i = 0; i < n; ++i)
			num += (!dead[i] && (arr[i] & (1<<j)));
		if (num >= k) {
			sol ^=	1<<j;
			for (int i = 0; i < n; ++i)
				dead[i] |= !(arr[i] & (1<<j));
		}
	}
	
	cout<<sol<<endl;
}