#include <bits/stdc++.h>
using namespace std;
struct dsu{
vector<int> sz,par;
dsu(int n): sz(n,1),par(n){
iota(par.begin(),par.end(),0);
}
int find(int a){
return a == par[a] ? a : par[a] = find(par[a]);
}
void unite(int a,int b){
a = find(a), b = find(b);
if(sz[a] < sz[b]) swap(a,b);
sz[a] += sz[b];
par[b] = a;
}
};
int main(){
int n,k;
cin >> n >> k;
vector<int> a(n);
for(auto &x: a){
cin >> x;
}
dsu d(n);
vector<pair<int,int>> edges;
for(int i = 0; i < n - 1; i++){
edges.emplace_back(a[i+1] - a[i], i);
}
sort(edges.begin(), edges.end());
vector<vector<int>> comp(n);
for(int i = 0; i < n - k; i++){
d.unite(edges[i].second,edges[i].second+1);
}
for(int i = 0; i < n; i++){
comp[d.find(i)].push_back(a[i]);
}
int ans = 0;
for(int i = 0; i < n; i++){
if(comp[i].size() == 1) ans++;
else if(comp[i].size() > 1) ans += comp[i].back() - comp[i][0] + 1;
}
cout << ans;
}
