#include <bits/stdc++.h>

#ifdef LOCAL
#include "../algo/debug.h"
#else 
#define debug(...) 0
#endif

using namespace std;

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  long long k;
  cin >> n >> k;
  vector<long long> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  vector now(2, vector<long long> (41));
  for (int b = 40; b >= 0; b--) {
    for (int i = 0; i < n; i++) {
      if (a[i] >> b & 1) {
        now[0][b] += 1ll << b;
      } else {
        now[1][b] += 1ll << b;
      }
    }
  }
  long long sum = 0, ans = 0;
  for (int i = 40; i >= 0; i--) {
    if (k >> i & 1) {
      long long p = sum + now[0][i];
      for (int j = i - 1; j >= 0; j--) {
        p += max(now[0][j], now[1][j]);
      }
      ans = max(ans, p);
      sum += now[1][i];
    } else {
      sum += now[0][i];
    }
  }
  ans = max(ans, sum);
  cout << ans << '\n';
  return 0;
}