#include <bits/stdc++.h>

bool debug=true;

#define ll long long
#define ull unsigned long long

#define log(var) if(debug) {cout << #var << ": " << (var) << endl;}
#define tr(container, it) \
	 for(typeof(container.begin() it = container.begin(); it != container.end(); it++)

using namespace std;
vector<int> filters{ 1<<30, 1<<29, 1<<28, 1<<27, 1<<26, 1<<25, 1<<24, 1<<23, 1<<22, 1<<21, 1<<20, 1<<19, 1<<18, 1<<17, 1<<16, 1<<15, 1<<14, 1<<13, 1<<12, 1<<11, 1<<10, 1<<9, 1<<8, 1<<7, 1<<6, 1<<5, 1<<4, 8, 4, 2, 1};

int log2(ll n){
	int res = 1;
	while (n>>=1)
		res++;
	return res;
	}

int main(){
int n,k;

cin >> n >> k;


vector<ll> is;
vector<bool> valid;
ll* remaining = new ll[n]();
for(ll i = 0; i<n; i++){
	remaining[i] = i;
	ll ahoj;
	cin >> ahoj;
	is.push_back(ahoj);
}

ll cntremaining=0;
int max = *max_element(is.begin(),is.end());


for(ll f = 0; f<30; f++){
cntremaining = 0;
	for(ll i = 0; i<n; i++){
		if(remaining[i] != -1){
			if(is[i] & filters[f])
			cntremaining += 1;
		}
	}

	if(cntremaining >= k){
		for(ll i = 0; i<n; i++){
			if(remaining[i] != -1){
				if(!(is[i] & filters[f]))
					remaining[i]=-1;
				}
			}
	}
}
		ll tempcode = 0;
			for(ll i = 0; i<n; i++){
				if( remaining[i] != -1){
					if(!tempcode){
						tempcode = is[remaining[i]];
					}
					else{
						tempcode &= is[remaining[i]];
					}
				}
			}

	cout << tempcode;
return 0;
}