#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define ff first
#define ss second
#define enld endl
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<ll,ll> pll;
const ll sz=2e5+100;
const ll mod=1e9+7;
const ll inf=1e18;
template<class T>
using indexed_set=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
void solve(){
ll n,k;
cin>>n>>k;
vector<ll> v(n);
sort(all(v));
for(ll i=0;i<n;i++) cin>>v[i];
ll ans=abs(v[0]-v[n-1]);
vector<ll> d;
for(ll i=0;i<n-1;i++) d.push_back(abs(v[i]-v[i+1])-1);
sort(rall(d));
for(ll i=0;i<k-1;i++) ans-=d[i];
cout<<ans+1;
}
int main(){
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
ll t=1;
//cin>>t;
for(ll _=1;_<=t;_++){
//cout<<"Scenario #"<<_<<":\n";
solve();
}
}
