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

const int N = 2e5 + 5;
int n, a[N], m, ans, k;

int main(){
    ios_base::sync_with_stdio(0);cin.tie(0);
    cin >>n>>k;
    for (int i = 1; i <= n; ++i){
        cin >>a[i];
    }
    for (int i = 29; i >= 0; --i){
        int m = 0;
        int t = 0;
        for (int j = 1; j <= n; ++j){
            if (a[j] & (1 << i))t++;
        }
        //cout <<t<<" "<<i<<" "<<(1 << i)<<" "<<n<<" "<<ans<<endl;
        if (t < k)continue;
        ans += (1 << i);
        for (int j = 1; j <= n; ++j){
            if (a[j] & (1 << i)){
                m++;
                a[m] = a[j];
            }
        }
        n = m;
    }
    cout <<ans;
}