#include <bits/stdc++.h> using namespace std; using ll = long long; #define int ll using P = pair<int, int>; #define all(x) x.begin(), x.end() #define rep(i, l, n) for (int i = l; i < (n); ++i) #define sz(x) (int)x.size() const char nl = '\n'; void solve() { int n, k; cin >> n >> k; vector<int> t(n); for (auto &i: t)cin >> i; priority_queue<int, vector<int>, greater<int>> pq; rep(i, 1, n)pq.push(t[i]-t[i-1]-1); int res = n, s = n; while (s > k) { res += pq.top(); pq.pop(); s--; } cout << res << nl; } int32_t main() { ios_base::sync_with_stdio(0); cin.tie(0); solve(); return 0; }