/* Leetcode 1696: Jump-Game-VI.  James S. Plank.
   Please see the accompanying writeup for how this works. */

/* Runtime: 535 ms, faster than 13.56% of C++ online submissions for Jump Game VI.
   Memory Usage: 135.8 MB, less than 5.44% of C++ online submissions for Jump Game VI.
   */

#include <iostream>
#include <vector>
#include <set>
using namespace std;

class Solution {
public:
    int maxResult(vector<int>& nums, int k);
};

int Solution::maxResult(vector<int>& nums, int k)
{
  vector <int> cache;
  multiset <int> window;    // This holds cache[i+1] through cache[min(i+k,n-1)].
  int i, j;

  cache.resize(nums.size());

  for (i = nums.size()-1; i >= 0; i--) {
    if (i == nums.size()-1) {
      cache[i] = nums[i];
    } else {
      cache[i] = nums[i] + *(window.rbegin());
    }
    window.insert(cache[i]);
    if (window.size() > k) {
      window.erase(window.find(cache[i+k]));
    }
  }
  return cache[0];
}

int main(int argc, char **argv)
{
  int k;
  vector <int> nums;
  Solution s;

  while (cin >> k) nums.push_back(k);
  nums.pop_back();
  cout << s.maxResult(nums, k) << endl;
  return 0;
}