#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define ar array
const int INF = 1e15;
const int MOD = 1e9+7;
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, k; cin>>n>>k;
vector<int> a(n);
for (int &i : a) cin>>i;
int sum = n;
sort(a.begin(), a.end());
vector<int> stuff;
for (int i = 0; i < n-1; i++) {
stuff.push_back(-(a[i]+1-a[i+1]));
}
sort(stuff.begin(), stuff.end());
for (int i = 0; i < n-k; i++) {
sum += stuff[i];
}
cout<<sum<<"\n";
}
