#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N=500010;
int n,k;
ll a[N],ans;
vector<ll>v;
bool cmp (ll x,ll y) {
    return x>y;
}
int main () {
    freopen("xor.in","r",stdin);
    freopen("xor.out","w",stdout);
    ios::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);
    cin >> n >> k;
    for (int i=1;i<=n;i++) cin >> a[i];
    for (int i=1;i<=n;i++) {
        ll sum=0;
        for (int j=i;j<=n;j++) {
            sum^=a[j];
            v.push_back(sum);
        }
    }
    sort(v.begin(),v.end(),cmp);
    for (int i=0;i<k;i++) {
        ans+=v[i];
    }
    cout << ans <<endl;
    return 0;
}