#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,k,s[500001],ans;
priority_queue<int> q;
signed main(){
    freopen("xor.in","r",stdin);
    freopen("xor.out","w",stdout);
    cin>>n>>k;
    for(int i=1;i<=n;i++){
        cin>>s[i];
        s[i]^=s[i-1];
    }
    for(int i=1;i<=n;i++){
        for(int j=i;j<=n;j++){
            q.push(s[j]^s[i-1]);
        }
    }
    while(k--){
        ans+=q.top();
        q.pop();
    }
    cout<<ans;
}