// #pragma GCC optimize("Ofast")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt")
// #define NDEBUG

#include <bits/extc++.h>
#include <x86intrin.h>

struct rep {
  struct iter {
    int i;
    constexpr void operator++() { ++i; }
    constexpr int operator*() const { return i; }
    friend constexpr bool operator!=(iter a, iter b) { return *a != *b; }
  };
  const int l, r;
  constexpr rep(int _l, int _r) : l(std::min(_l, _r)), r(_r) {}
  constexpr rep(int n) : rep(0, n) {}
  constexpr iter begin() const { return {l}; }
  constexpr iter end() const { return {r}; }
};
struct per {
  struct iter {
    int i;
    constexpr void operator++() { --i; }
    constexpr int operator*() const { return i; }
    friend constexpr bool operator!=(iter a, iter b) { return *a != *b; }
  };
  const int l, r;
  constexpr per(int _l, int _r) : l(std::min(_l, _r)), r(_r) {}
  constexpr per(int n) : per(0, n) {}
  constexpr iter begin() const { return {r - 1}; }
  constexpr iter end() const { return {l - 1}; }
};
template <class T, class U>
constexpr bool chmin(T& a, U&& b) {
  return b < a ? a = std::forward<U>(b), true : false;
}
template <class T, class U>
constexpr bool chmax(T& a, U&& b) {
  return a < b ? a = std::forward<U>(b), true : false;
}

int main() {
  using namespace std;
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, x;
  cin >> n >> x;
  map<int, int64_t> dp;
  dp[x] = 0;
  while (n--) {
    int a;
    cin >> a;
    map<int, int64_t> ndp;
    for (auto [k, v] : dp) {
      chmax(ndp[k & a], v + abs((k & a) - k));
      chmax(ndp[k | a], v + abs((k | a) - k));
    }
    dp = move(ndp);
  }
  int64_t ans{};
  for (auto [k, v] : dp) chmax(ans, v);
  cout << ans << '\n';
}