#include<bits/stdc++.h> using namespace std; using i64 = int64_t; int main() { ios_base::sync_with_stdio(0); cin.tie(0); int N, K; cin >> N >> K; vector<int> roz(N - 1); vector<int> gos(N); for (int i = 0; i < N; i++) { cin >> gos[i]; if (i != 0) { roz[i - 1] = gos[i] - gos[i - 1] - 1; } } sort(roz.rbegin(), roz.rend()); int wynik = gos[N - 1] - gos[0] + 1; for (int i = 0; i < K - 1; i++) { wynik -= roz[i]; } cout << wynik << "\n"; return 0; }