#include <bits/stdc++.h> using namespace std; #define fi first #define se second #define mp make_pair #define pb push_back #define eb emplace_back #define all(x) x.begin(), x.end() typedef long long ll; typedef pair<int, int> pii; const int N = 1e5 + 3; int n, k, a[N]; void solve() { cin >> n >> k; for (int i = 1; i <= n; ++i) cin >> a[i]; vector<int> tmp; int ans = a[n] - a[1]; for (int i = 1; i < n; ++i) tmp.pb(a[i + 1] - a[i]); sort(all(tmp), greater<int> ()); for (int i = 0; i < k - 1; ++i) ans -= tmp[i]; cout << ans + k; } int main() { cin.tie(NULL); ios_base::sync_with_stdio(false); solve(); return 0; }