#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <fstream>
#include <exception>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <climits>
#include <list>
#include <cmath>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdio.h>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#define int long long
#define MOD 1000000007
#define all(x) x.begin(), x.end()
#define fast_io ios_base::sync_with_stdio(false); cin.tie(nullptr);
using namespace std;
void solution(){
int n,k; cin >> n >> k;
vector<int> arr(n);
for(int &i : arr) cin >> i;
int n_ans = 1;
int ans = 1;
sort(all(arr));
for(int i = 0; i < n-1; i++){
if(arr[i+1] - arr[i] > 1){
n_ans++;
ans++;
}else{
ans++;
}
}
vector<int> track;
for(int i = 0; i < n-1; i++){
if(arr[i+1] - arr[i] > 1)
track.push_back(arr[i+1] - arr[i] - 1);
}
sort(all(track));
int idx = 0;
// cout << ans << " " << n_ans << endl;
while(n_ans > k){
// cout << track[idx] << endl;
ans += track[idx];
idx++;
n_ans -= 1;
}
cout << ans << endl;
}
signed main(){
fast_io;
int t = 1;
// cin >> t;
while (t--) {
solution();
}
return 0;
}
