#include <iostream>
#include <vector>
#include <algorithm>
#include <queue>
using namespace std;
struct Inter {
int deb, fin;
};
bool comp(const Inter& a, const Inter& b)
{
if (a.deb == b.deb)
return a.fin < b.fin;
return a.deb < b.deb;
}
signed main(void)
{
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int nbIntervallesPre, nbAllumettes;
cin >> nbIntervallesPre >> nbAllumettes;
vector<Inter> intervallesPre(nbIntervallesPre);
for (int _ = 0; _ < nbIntervallesPre; _++)
{
cin >> intervallesPre[_].deb;
intervallesPre[_].fin = intervallesPre[_].deb + 1;
}
sort(intervallesPre.begin(), intervallesPre.end(), comp);
vector<Inter> intervalles;
intervalles.push_back(intervallesPre[0]);
for (int i = 1; i < nbIntervallesPre; i++)
{
if (intervallesPre[i - 1].fin == intervallesPre[i].deb)
{
intervalles.pop_back();
intervalles.push_back({intervallesPre[i - 1].deb, intervallesPre[i].fin});
intervallesPre[i] = intervalles[i - 1];
}
else
intervalles.push_back(intervallesPre[i]);
}
int nbIntervalles = (int)intervalles.size();
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
for (int i = 1; i < nbIntervalles; i++)
pq.push({intervalles[i].fin - intervalles[i - 1].fin, i});
int total = 0;
for (int i = 0; i < nbIntervalles - nbAllumettes; i++)
{
total += intervalles[pq.top().second].deb - intervalles[pq.top().second - 1].fin;
pq.pop();
}
for (auto inter : intervalles)
total += (inter.fin - inter.deb);
cout << total << "\n";
return 0;
}
