#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int n, k;
vector<ll> t;
int main(){
cin >> n >> k;
t.resize(n);
for(int i = 0; i < n; i++) cin >> t[i];
if(n <= k){
cout << n;
return 0;
}
vector<pair<ll, pair<ll, ll>>> pos(n - 1);
for(int i = 0; i < n - 1; i++){
int p = t[i + 1] - t[i];
pos[i].first = p;
pos[i].second = {i, i + 1};
}
sort(pos.begin(), pos.end());
//for(int i = 0; i < n - 1; i++) cout << pos[i].second.first << ' ' << pos[i].second.second << " , cost - " << pos[i].first << '\n'; cout << '\n';
vector<pair<pair<ll, ll>, ll>> tmp;
for(int i = 0; i < n - k; i++) tmp.push_back({{pos[i].second.first + 1, pos[i].second.second + 1}, pos[i].first});
int m = tmp.size();
sort(tmp.begin(), tmp.end());
//for(int i = 0; i < m; i++) cout << tmp[i].first.first << ' ' << tmp[i].first.second << '\n'; cout << '\n';
map<ll, ll> parent;
for(int i = 0; i < m; i++){
if(parent[tmp[i].first.first] == 0) parent[tmp[i].first.second] = tmp[i].first.first;
else{
parent[tmp[i].first.second] = parent[tmp[i].first.first];
parent[tmp[i].first.first] = 0;
}
}
ll ans = 0;
ll last = 0;
for(auto x: parent){
if(x.first != 0 && x.second != 0){
ans += t[x.first - 1] - t[x.second - 1] + 1;
last++;
}
}
ans += (k - last);
cout << ans;
//for(auto x: pos) cout << x.first << ' ' << x.second.first << ' ' << x.second.second << '\n';
}
