#include<bits/stdc++.h>
using namespace std;
#define pb push_back
#define ll long long
const int lim=100005;
vector<int>v[lim];
void solve(){
int n,k;
cin>>n>>k;
vector<ll> aralik;
vector<ll> sayilar;
ll x;
for(int i=0;i<n;i++){
ll x;
cin>>x;
sayilar.pb(x);
sayilar.pb(x+1);
}
for(ll i=0;i+1<n;i++){
aralik.pb(sayilar[(i*2)+2]-sayilar[(i*2)+1]);
}
/*for(int i=0;i<n;i++){
cout<<aralik[i]<<" ";
}*/
//cout<<endl;
sort(aralik.begin(),aralik.end());
aralik.pb(sayilar[0]-0);
ll toplam=sayilar[2*n-1];
ll sayac=n-1;
for(int i=k;i>0;i--){
toplam-=aralik[sayac];
sayac--;
}
cout<<toplam<<endl;
}
signed main(){
ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
solve();
}
