#include <bits/stdc++.h>
#include <math.h>
//in the name of god,aka allah
//**gray sety orz**
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("-fgcse")
#pragma GCC optimize("-fgcse-lm")
#pragma GCC optimize("-fipa-sra")
#pragma GCC optimize("-ftree-pre")
#pragma GCC optimize("-ftree-vrp")
#pragma GCC optimize("-fpeephole2")
#pragma GCC optimize("-fsched-spec")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("-falign-jumps")
#pragma GCC optimize("-falign-loops")
#pragma GCC optimize("-falign-labels")
#pragma GCC optimize("-fdevirtualize")
#pragma GCC optimize("-fcaller-saves")
#pragma GCC optimize("-fcrossjumping")
#pragma GCC optimize("-fthread-jumps")
#pragma GCC optimize("-funroll-loops")
#pragma GCC optimize("no-stack-protector")
#pragma GCC optimize("-freorder-functions")
#pragma GCC optimize("-findirect-inlining")
#pragma GCC optimize("-fhoist-adjacent-loads")
#pragma GCC optimize("-frerun-cse-after-loop")
#pragma GCC optimize("-ftree-switch-conversion")
#pragma GCC optimize("-foptimize-sibling-calls")
#pragma GCC optimize("-fexpensive-optimizations")
#pragma GCC optimize("-fdelete-null-pointer-checks")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,tune=native")
#pragma GCC optimize("unroll-loops")
using namespace std;
#define pi pair<long long , long long>
#define pii pair<long long , pair<long long , long long>>
const int maxm = 5e5;
const long long mod = 1e9 + 7 ;
typedef long long ll;
ll l,r,mid;
ll n,m;
ll dis[maxm] , sum[maxm];
bool isval(int mid){
//cout << mid <<" " << mid*mid-mid <<endl;
if (((mid-1)*mid)/2 < m) return 0;
return 1;
}
ll darage[maxm] , ss , mm;
queue<int> q;
vector<ll> g[maxm] , z[maxm];
ll sath[maxm];
bool vis[maxm] , gos[maxm];
ll pedaret[maxm];
ll get_par(ll v){
if (pedaret[v]==v) return v;
return pedaret[v] = get_par(pedaret[v]);
}
void merge(ll r , ll q){
if (get_par(r)!=get_par(q))l+=max(darage[r],darage[q])*1ll*sath[r]*1ll*sath[q];
r = get_par(r) , q = get_par(q);
if (r!=q){
if (sath[r]<sath[q]) swap(r,q);
pedaret[q] = r;
sath[r] += sath[q];
}
return ;
}
ll pars1[maxm] , pars2[maxm];
vector<ll> se[maxm];
set<int> st;
ll rp[maxm];
pi w[maxm];
ll dp[maxm];
//ll rw[maxm][maxm];
map<ll,ll> mp;
int main(){
ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
cin >>n>>m;
for (int i=0; i<n; i++){
cin>>pedaret[i];
}
sort(pedaret,pedaret+n);
for (int i=0; i<n-1; i++){
darage[i] = pedaret[i+1]-pedaret[i]-1;
}
sort(darage,darage+n-1);
for (int i=0; i<n-m; i++) mid+=darage[i];
cout<<mid+n;
}
