#include <bits/stdc++.h>
using namespace std;
#define fastio ios::sync_with_stdio(false); cin.tie(nullptr);
#define s(x) x.size()
#define sort(x) sort(x.begin(),x.end())
#define rsort(x) sort(x.rbegin(),x.rend())
#define all(x) (x).begin(), (x).end()
#define pb push_back
#define fi first
#define se second
#define INF 1e9
#define INFL 1e18
#define rep(a,b) for(int a = 0;a<b;a++)
using ll = long long;
using pii = pair<int, int>;
void solve() {
int n,k;
cin >> n >> k;
vector<int>v(n);
for (int i = 0; i < n; i++) {
cin >> v[i];
}
sort(v);
priority_queue<int>kolejka;
int wynik = n;
k-=n;
for (int i = 0; i < n-1; i++) {
kolejka.push((v[i+1]-v[i]-1)*-1);
}
while(!kolejka.empty() && k<0){
wynik+=kolejka.top()*-1;
k++;
kolejka.pop();
// cout << k << endl;
}
cout << wynik << endl;
}
int main() {
fastio;
int t = 1;
// cin >> t;
while (t--) solve();
return 0;
}
