#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
#define ll long long
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) < (b)) ? (b) : (a))
int const nmax = 100000;
int v[1 + nmax];
int v2[1 + nmax];
int main()
{
int n, k;
cin >> n >> k;
for(int i = 1;i <= n; i++)
cin >> v[i];
sort(v + 1, v + n + 1);
for(int i = 1;i < n; i++){
v2[i] = v[i + 1] - v[i] - 1;
}
sort(v2 + 1, v2 + n);
int time = n;
for(int i = 1; i <= n - k; i++){
time += v2[i];
}
cout << time;
return 0;
}
