#include "bits/stdc++.h" using namespace std; using ll = long long; using pii = pair<int, int>; int main() { cin.tie(0)->sync_with_stdio(0); int n, k; cin >> n >> k; vector<int> a(n + 5); priority_queue<int> Q; for (int i = 1; i <= n; i++) { cin >> a[i]; if (i > 1) { Q.push(a[i] - a[i - 1] - 1); } } int ans = a[n] - a[1] + 1; for (int i = 1; i <= k - 1; i++) { ans -= Q.top(); Q.pop(); } cout << ans << endl; }