#include <bits/stdc++.h>

using namespace std;

#define ll              long long
#define pb              push_back
#define mp              make_pair
#define forn( i, n )    for( ll i = 0; i < (ll) (n); i ++ )
#define endl            '\n'

ll n, m, k;
vector< ll > a;
ll ans;

int main( void ) {
    cin >> n >> m;
    forn( i, n ) {
        ll aa;
        cin >> aa;
        a.pb( aa );
    }
    for( ll i = 32; i >= 0; i -- ) {
        ll k = ( 1LL << i );
        vector< ll > res;
        forn( j, a.size() ) {
            if( a[j] & k ) {
                res.pb( j );
            }
        }
        if( res.size() % 2 ) {
            ans += k;
            continue;
        }
        vector< ll > b;
        ll l = 0;
        for( ll j = 0; j < res.size(); j += 2 ) {
            while( l < res[j] ) {
                b.pb( a[l] );
                l ++;
            }
            ll sum = 0;
            for( ll ii = res[j]; ii <= res[j + 1]; ii ++ )
                sum = sum ^ a[ii];
            b.pb( sum );
            l = res[j + 1] + 1;
        }
        while( l < a.size() ) {
            b.pb( a[l] );
            l ++;
        }
        if( b.size() < m ) {
            ans += k;
            continue;
        }
        a = b;
    }
    cout << ans << endl;
    return 0;
}