#include <bits/stdc++.h>
using namespace std;
#define speed ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
#define ll long long
#define pb push_back
#define S second
#define F first
#define pll pair<ll,ll>
#define pii pair<int,int>
void solve(){
int n,k;
cin>>n>>k;
if(n==k){cout<<k;return;}
ll a[n];
vector <ll> dif;
for(int i=0;i<n;i++)cin>>a[i];
sort(a,a+n);
ll sum=a[n-1]-a[0]+1;
for(int i=0;i<n-1;i++)dif.pb(a[i+1]-a[i]-1);
sort(dif.begin(),dif.end());
for(int i=dif.size()-1;i>=dif.size()-k+1;i--){
sum-=dif[i];
}
cout<<sum;
}
int main() {
solve();
return 0;
}
