#include <bits/stdc++.h>
#include <fstream>
#define endl '\n'
#define mod 998244353
#define INF 100000000
//#define ll long long
///#define cin fin
///#define cout fout
#define fi first
#define se second
using namespace std;
///ofstream fout("herding.out");
///ifstream fin("herding.in");
int main()
{
ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
int n, k, ans; cin >> n >> k; int arr[n]; ans = n;
for(int i = 0; i < n; i++) cin >> arr[i];
sort(arr,arr+n); vector<int> dis;
for(int i = 1; i < n; i++) {
dis.push_back(arr[i]-arr[i-1]-1);
}
sort(dis.begin(),dis.end());
for(int i = 0; i < n-k; i++) ans += dis[i];
cout << ans;
return 0;
}
