#include<bits/stdc++.h>

using namespace std;

const int maxn=2e5+;

int n,m,a[maxn],nxt[maxn],lst[maxn],ans,mov[maxn];

struct node{int k;};

bool operator < (node x,node y) {return a[x.k]<a[y.k];};

priority_queue<node> q;

int main()

{

    scanf("%d%d",&n,&m);

    if (n<m*)

    {

        printf("Error!");

        return ;

    }

    for (int i=;i<=n;i++) scanf("%d",&a[i]),q.push((node){i});

    for (int i=;i<n;i++) nxt[i]=i+;nxt[n]=;

    for (int i=;i<=n;i++) lst[i]=i-;lst[]=n;

    while(m--)

    {

        node now=q.top();q.pop();

        while(mov[now.k])

        {

            now=q.top();

            q.pop();

        }

        ans+=a[now.k];

        a[now.k]=a[lst[now.k]]+a[nxt[now.k]]-a[now.k];

        mov[lst[now.k]]=;

        mov[nxt[now.k]]=;

        lst[now.k]=lst[lst[now.k]],nxt[lst[now.k]]=now.k;

        nxt[now.k]=nxt[nxt[now.k]],lst[nxt[now.k]]=now.k;

        q.push((node){now.k});

    }

    printf("%d",ans);

    return ;

}