#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define yes cout << "YES\n"
#define no cout << "NO\n"
#define F first
#define S second
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(), (x).end()
void solve(){
int n, k;
cin >> n >> k;
int a[n];
for(int i=0; i< n; i++){
cin >> a[i];
}
sort(a, a+n);
int ans=a[n-1]-a[0]+1;
vector<int> rz;
for(int i=1; i<n; i++){
rz.pb(a[i]-a[i-1]-1);
}
sort(rz.begin(), rz.end());
k--;
int p=rz.size()-1;
while(k--){
ans-=rz[p];
p--;
}
cout << ans << '\n';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int t=1;
//cin >> t;
while(t--){
solve();
}
}
