#include <bits/stdc++.h>

using namespace std;
void fast_io() {
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
}
int main() {
    fast_io();
    int n, t;
    cin >> n >> t;
    vector<int> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    map<int, long long> dp;
    dp[t] = 0;
    for (int i = 0; i < n; i++) {
        map<int, long long> ndp;
        for (auto [k, v] : dp) {
            ndp[k | a[i]] = max(ndp[k | a[i]], v + abs(k - (k | a[i])));
            ndp[k & a[i]] = max(ndp[k & a[i]], v + abs(k - (k & a[i])));
        }
        swap(dp, ndp);
    }
    long long ans = 0;
    for (auto [k, v] : dp) {
        ans = max(ans, v);
    }
    cout << ans << endl;
}