#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define pii pair<long long int,long long int>
#define vi vector<long long int >
#define vvi vector<vector< long long int>>
#define MP make_pair
#define PB push_back
#define pb pop_back
#define PF push_front
#define pf pop_front
#define MOD 1000000007
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
ll n,k;
cin>>n>>k;
vi arr(n);
for(ll i=0;i<n;i++)
{
cin>>arr[i];
}
sort(arr.begin(),arr.end());
vi diff(n-1);
for(ll i=0;i<n-1;i++)
{
if(arr[i]==arr[i+1])
diff[i]=0;
else
diff[i]=arr[i+1]-arr[i]-1;
}
sort(diff.begin(),diff.end());
ll ans=arr[n-1]-arr[0]+1;
ll c= k-1;
ll i=n-2;
while(i>=0 && c>0)
{
ans-=diff[i];
i--;
c--;
}
cout<<ans<<"\n";
return 0;
}
