#include<bits/stdc++.h>
#define ll long long
#define N 500001
using namespace std;
ll n,k,a[N],b[N],ans[1000001],cnt,sum;
int main(){
    freopen("xor.in","r",stdin);
    freopen("xor.out","w",stdout);
    cin>>n>>k;
    for(int i=1;i<=n;i++){
        cin>>a[i];
        b[i]=b[i-1]^a[i];
    }
    for(int l=1;l<=n;l++)
    for(int r=l;r<=n;r++) ans[++cnt]=b[r]^b[l-1];
    sort(ans+1,ans+n*n+1,greater<ll>());
    for(int i=1;i<=k;i++) sum+=ans[i];
    cout<<sum<<endl;
    return 0;
}