#include<iostream>
#include<bits/stdc++.h>
using namespace std;
#define ll long long

ll n,k;
ll a[510000]; 
ll res[11000000],cnt;
ll ans;

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];
		a[i]=a[i]^a[i-1];
	}
	for(int i=1;i<=n;i++){
		for(int j=i;j<=n;j++){
			res[++cnt]=a[j]^a[i-1];
		}
	}
	sort(res+1,res+cnt+1);
	for(int i=cnt;i>=cnt-k+1;i--){
		ans+=res[i];
	}
	cout<<ans<<'\n';
	return 0;
}