#include <bits/stdc++.h> using namespace std; int n,k,a[100005]; priority_queue <int> pq; int main(){ iostream::sync_with_stdio(0); cin >> n >> k; for(int i=1;i<=n;i++) cin >> a[i]; for(int i=1;i<n;i++) pq.push(a[i+1] - a[i] - 1); int res = a[n] - a[1] + 1; k --; while(k--){ res -= pq.top(); pq.pop(); } cout << res; }