#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
int n,k;
long long s[500005];
struct node{
    int l,r;
    long long val;
}b[10000005];
int cnt;
long long ans;
bool cmp(node x,node y){
    return x.val>y.val;
}
int main(){
    freopen("xor.in","r",stdin);
    freopen("xor.out","w",stdout);
    scanf("%d%d",&n,&k);
    for(int i=1;i<=n;i++){
        scanf("%lld",&s[i]);
        s[i]=s[i-1]^s[i];
    }
    for(int i=1;i<=n;i++){
        for(int j=i;j<=n;j++){
            b[++cnt]={i,j,s[j]^s[i-1]};
        }
    }
    sort(b+1,b+1+cnt,cmp);
    for(int i=1;i<=k;i++){
        ans+=b[i].val;
    }
    printf("%lld",ans);
    return 0;
}