#include <bits/stdc++.h>
using namespace std;
const int N = 1e3 + 10;
long long n, k;
long long tmp, ans;
long long z[N];
priority_queue<long long>q;
int main(){
    freopen("xor.in", "r", stdin);
    freopen("xor.out", "w", stdout);
    cin >> n >> k;
    for(int i = 1;i <= n;i++){
        cin >> z[i];
        q.push(z[i]);
    }
    for(int i = 1;i <= n;i++){
        tmp = z[i];
        for(int j = i + 1;j <= n;j++){
            tmp ^= z[j];
            q.push(tmp);
        }
    }
    while(k--){
        ans += q.top();
        q.pop();
    }
    cout<<ans<<endl;
}