#include <bits/stdc++.h>
#include <sstream>
using namespace std;
#define accepted ios_base::sync_with_stdio(false);cin.tie(nullptr);
#define Daulbekov signed
#define Makan main
#define int long long
#define double long double
#define pb push_back
#define pf push_front
#define F first
#define S second
const int N=1e5+7;
const int MAX=9e18+7;
const int INF=1e18;
Daulbekov Makan(){
int n,k;
cin>>n>>k;
k--;
int a[n];
for(int i=0;i<n;i++)cin>>a[i];
sort(a,a+n);
int x[n-1],ans=0;
for(int i=0;i<n-1;i++){
x[i]=a[i+1]-a[i];
ans+=x[i];
}
sort(x,x+n-1);
for(int i=n-2;i>=0;i--){
// cout<<x[i]<<" ";
if(k>=1){
ans-=x[i];
ans+=1;
k--;
}
else{
break;
}
}
cout<<ans+1;
}
// 1 2 5 6 8 11 13 16 20
// 2 4 2 3 4 3 4 5
// 2 1 2 3 1 1 1 1
