// https://oj.uz/problem/view/JOI18_stove
#include<bits/stdc++.h>
#define endl '\n'
using namespace std;
void Solve() {
int N, K;
cin >> N >> K;
vector<int>T;
int ans = N;
for(int i = 1; i <= N; ++i) {
int ti;
cin >> ti;
T.push_back(ti);
}
sort(T.rbegin(), T.rend());
vector<int>dif;
for(int i = 1; i <= N - 1; ++i) {
int df = T[i] - T[i + 1];
dif.push_back(df);
}
for(int i = 0; i < N - K; ++i) {
ans+=dif[i];
}
cout << --ans << endl;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
Solve();
return 0;
}
