#include <bits/stdc++.h>
#define ff first
#define ss second
#define endl '\n'
using namespace std;
const long long INF = (long long) 1e18;
const int mod = (int) 1e9+7;
const int MAXN = (int) 3e5+5;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
ll n, k;
priority_queue<int, vector<int>, greater<int>> q;
int a[MAXN];
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);cout.tie(nullptr);
#ifdef Local
freopen("C:/Users/Admin/Desktop/Yazilim/C/IO/int.txt","r",stdin);
freopen("C:/Users/Admin/Desktop/Yazilim/C/IO/out.txt","w",stdout);
#endif
cin>>n>>k;
for(int i = 0; i < n; i++){
cin>>a[i];
}
sort(a, a + n);
ll ans = n;
for(int i = 1; i < n; i++) q.push(a[i] - a[i - 1] - 1);
for(int i = 0; i < n - k; i++){
ans += q.top();
q.pop();
}
cout<<ans<<endl;
#ifdef Local
cout<<endl<<fixed<<setprecision(2)<<1000.0 * clock() / CLOCKS_PER_SEC<< " milliseconds ";
#endif
}
