#include <bits/stdc++.h>
#define ll long long
using namespace std;
int n,k;
ll a[500010];
priority_queue<ll>q;
ll ans;
int main()
{
    freopen("xor.in","r",stdin);
    freopen("xor.out","w",stdout);
    ios::sync_with_stdio(false);
    cin.tie(nullptr);cout.tie(nullptr);
    cin>>n>>k;
    for(int i=1;i<=n;i++) cin>>a[i];
    for(int i=1;i<=n;i++) a[i]=a[i]^a[i-1];
    for(int i=1;i<=n;i++)
        for(int j=0;j<i;j++)
            q.push(a[i]^a[j]);
    for(int i=1;i<=k;i++)
    {
        ans+=q.top();
        q.pop();
    }
    cout<<ans;
    return 0;
}