#include<cstdio>

 #include<cstdlib>

 #include<cmath>

 #include<cstring>

 #include<algorithm>

 #include<iostream>

 #include<vector>

 #include<map>

 #include<set>

 #include<queue>

 #include<string>

 #define inf 1000000000

 #define maxn 200000+5

 #define maxm 100000+5

 #define eps 1e-10

 #define ll long long

 #define pa pair<int,int>

 #define for0(i,n) for(int i=0;i<=(n);i++)

 #define for1(i,n) for(int i=1;i<=(n);i++)

 #define for2(i,x,y) for(int i=(x);i<=(y);i++)

 #define for3(i,x,y) for(int i=(x);i>=(y);i--)

 #define for4(i,x) for(int i=head[x],y=e[i].go;i;i=e[i].next,y=e[i].go)

 #define mod 1000000007

 using namespace std;

 inline int read()

 {

     int x=,f=;char ch=getchar();

     while(ch<''||ch>''){if(ch=='-')f=-;ch=getchar();}

     while(ch>=''&&ch<=''){x=*x+ch-'';ch=getchar();}

     return x*f;

 }

 int n,m,a[maxn],l[maxn],r[maxn];

 priority_queue<pa>q;

 int main()

 {

     freopen("input.txt","r",stdin);

     freopen("output.txt","w",stdout);

     n=read();m=read();

     if(m>n>>){printf("Error!\n");return ;}

     for1(i,n)a[i]=read(),l[i]=i-,r[i]=i+,q.push(pa(a[i],i));

     l[]=n;r[n]=;

     int ans=;

     for1(i,m)

     {

         while(!q.empty()&&q.top().first!=a[q.top().second])q.pop();

         int x=q.top().second;q.pop();

         ans+=a[x];

         a[x]=a[l[x]]+a[r[x]]-a[x];q.push(pa(a[x],x));

         a[l[x]]=a[r[x]]=inf;

         r[l[x]=l[l[x]]]=x;l[r[x]=r[r[x]]]=x;

     }

     cout<<ans<<endl;

     return ;

 }