#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;
typedef long long ll;
ll a[500005],b[1000006]; 
int main(){
    freopen("xor.in","r",stdin);
    freopen("xor.out","w",stdout);
    int n,k;
    cin>>n>>k;
    for(int i=1;i<=n;i++){
        cin>>a[i];
    }
    int cnt=0;
    for(int i=1;i<=n;i++){
        ll now=0;
        for(int j=i;j<=n;j++){
            now^=a[j];
            b[++cnt]=now;
        }
    }
    sort(b+1,b+1+cnt,greater<ll>());
    ll ans=0;
    for(int i=1;i<=k;i++) {
        ans+=b[i];
    }
    cout<<ans;
    return 0;
}