#include <bits/stdc++.h>
#define ll long long int
#define f first
#define s second
#define pii pair<int,int>
#define pll pair<long long,long long>
#define PB push_back
#define PF push_front
#define MOD 1000000007
#define intxt freopen("input.txt","r",stdin)
#define outtxt freopen("output.txt","w",stdout)
using namespace std;
const int MAXN = 2e5 + 10;
int n ,k ,a[MAXN];
vector <int> v;
int main() {
ios_base::sync_with_stdio(0);
cin >> n >> k;
for(int i = 1 ; i <= n ; i++) {
cin >> a[i];
}
sort(a + 1 , a + n + 1);
for(int i = 2 ; i <= n ; i++) {
v.PB(a[i] - a[i - 1] - 1);
}
sort(v.begin() , v.end());
int ans = n;
for(int i = 0 ; i < n - k ; i++) {
ans += v[i];
}
cout << ans;
}
//Hello
