#include <bits/stdc++.h> using namespace std; int main() { int n, k, ans = 0; cin >> n >> k; vector< int > a(n); for (int i = 0; i < n; i++) cin >> a[i]; for (int i = 1; i < n; i++){ a.push_back(a[i] - a[i - 1] - 1); } sort(a.begin() + n, a.end()); for (int i = 0; i < n - k; i++){ ans += a[n + i]; } cout << ans + n << endl; }