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

#define FOR(i, a, b) for (int i = (int)(a); i < (int)(b); ++i)
#define REP(i, n) FOR(i, 0, n)
#define TRACE(x) cerr << #x << " = " << x << endl
#define _ << " _ " <<

#define pb push_back
#define x first
#define y second

typedef long long ll;
typedef long double lf;

const int MAXN = 2e5 + 10;

int n, k;

vector<int> niz;

int main(void) {
  scanf("%d %d", &n, &k);
  REP(i, n) {
    int x;
    scanf("%d", &x);
    niz.push_back(x);
  }
  int rj = 0;
  for(int bit = 29; bit >= 0; bit--) {
    int brojac = 0;
    REP(i, (int) niz.size()) {
      if(niz[i] & (1 << bit))
        brojac++;
    }
    if(brojac >= k) {
      vector<int> novi;
      REP(i, (int) niz.size())
        if(niz[i] & (1 << bit))
          novi.push_back(niz[i]);
      niz = novi;
      rj += (1 << bit);
    }
  }
  printf("%d\n", rj);
  return 0;
}