#include<cstdio>

#include<cstring>

#include<iostream>

#include<algorithm>

using namespace std;

int n,m,ans;

int num[],sum[];

int cmp(int a,int b){

    return a>b;

}

int main(){

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

    for(int i=;i<=n;i++)    scanf("%d",&num[i]);

    for(int i=;i<n;i++)    sum[i]=num[i+]-num[i],ans+=sum[i];

    sort(sum+,sum+n,cmp);

    for(int i=;i<m;i++)    ans-=sum[i];

    cout<<ans+m;

}