#include<bits/stdc++.h>
using namespace std;
using ll = long long;
struct inter{
int start;
int end;
};
const int MAX_SIZE = (1<<18)+1;
const int LEAF = 1<<17;
pair<int,int> BT[MAX_SIZE];
pair<int,int> maxiPAIR(pair<int,int>a,pair<int,int>b){
if(a.first>b.first){
return a;
}else{
return b;
}
}
void fillBT(vector<int> &a){
for(int i = 0 ; i<MAX_SIZE;i++){
BT[i] = {-1,-1};
}
for(int i = 0 ; i < a.size();i++){
BT[i+LEAF] = {a[i],i};
}
for(int i = LEAF-1;i>=1;i--){
BT[i] = maxiPAIR(BT[2*i],BT[2*i+1]);
}
}
pair<int,int> requestMAX(int a,int b){
if(a==b)return BT[a];
if(a>b)return {-1,-1};
if(a&1){
return maxiPAIR(BT[a],requestMAX(a+1,b));
}else if(!(b&1)){
return maxiPAIR(BT[b],requestMAX(a,b-1));
}else{
return requestMAX(a/2,b/2);
}
}
pair<int,int> maxiBT(int a,int b){
return requestMAX(a+LEAF,b+LEAF);
}
bool operator<(inter const a,inter const b){
return maxiBT(a.start,a.end-1).first>maxiBT(b.start,b.end-1).first;
}
int main(){
int n,k;cin>>n>>k;
vector<int> t(n);
for(int i = 0 ; i < n ; i ++){
cin>>t[i];
}
sort(t.begin(),t.end());
vector<pair<int,int>> delay;
for(int i = 0 ; i < n-1;i++){
delay.push_back({t[i+1]-t[i],i});
}
sort(delay.rbegin(),delay.rend());
vector<int> indice;
for(int i=0;i<min(n,k-1);i++){
indice.push_back(delay[i].second);
}
sort(indice.begin(),indice.end());
indice.push_back(n-1);
int mini=-1;
int ind=0;
int score=0;
for(int i = 0 ; i <n;i++){
if(mini==-1){
mini = t[i];
}
if(i==indice[ind]){
ind++;
score+=t[i]-mini+1;
mini=-1;
}
}
cout<<score<<endl;
return 0;
}
