//do u need something?
#include <bits/stdc++.h>
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/t_policy.hpp>
using namespace __gnu_pbds;
//*/
/*
#pragma GCC optimization ("O3")
#pragma GCC target ("avx2")
#pragma GCC optimization ("unroll-loops")
//*/
std::mt19937 rng(std::chrono::system_clock::now().time_since_epoch().count());
using namespace std;
#define IO ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define y1 asjfkgasj
#define all(v) (v).begin(),(v).end()
#define pb push_back
#define F first
#define S second
#define endl '\n'
#define flsh '\n'<<flush
#define mp make_pair
#define mt make_tuple
#define sz size
#define pii pair<int,int>
#define pll pair<long long,long long>
#define vi vector<int>
#define vll vector<long long>
#define deb(x) cout<< #x <<'='<< x <<flsh;
#define iii int,int,int
#define ull unsigned long long
#define intt long long
#define ll long long
#define ld long double
#define dd double
#define OK cout<<"OK\n"<<flsh;
#define setpre(x) fixed<<setprecision(x)
#define mmset(x,y) memset(x,y,sizeof(x))
int n,k,ans,a[100001];
vector<int>v;
int main()
{
IO;
cin>>n>>k;
ans=n;
for(int i=0;i<n;i++)
cin>>a[i];
sort(a,a+n);
for(int i=1;i<n;i++)
v.pb(a[i]-a[i-1]);
sort(all(v));
for(int i=0;i<n-k;i++)
ans+=v[i]-1;
cout<<ans;
return 0;
}
