#include <bits/stdc++.h>
using namespace std;
#define IOS ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define mp make_pair
#define pb push_back
#define ll long long
#define ld long double
#define debug(x) cout << '[' << #x << " is: " << x << "] " << endl;
#define rsor(v) sort(v.rbegin() , v.rend());
#define rev(v) reverse(v.begin() , v.end());
#define sz(x) (int)(x).size()
#define all(x) x.begin(), x.end()
#define _cout(v) for(auto f : v ) cout << f << " " ;
#define _cin(v) for(auto &it : v)cin >> it ;
#define _for(v) for(int i=0;i<(v);i++)
#define vi vector<int>
#define fs first
#define sc second
const int mod =1e9+7;
int32_t main() {
IOS;
int n,k;
cin>>n>>k;
vector<int>a(n);
for(auto &I:a)cin>>I;
sort(all(a));
vi v;
for(int i=1;i<n;i++){
v.pb(a[i]-a[i-1]-1);
}
sort(all(v));
int ans=n;
for(int i=0;i<n-k;i++){
ans+=v[i];
}
cout<<ans;
}
