#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
signed main() { 
  ios::sync_with_stdio(false); cin.tie(0);
  int n, k, m;
  cin >> n >> k >> m;
  vector<int> a(n + 1);
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  vector<long long> sum(n + 1);
  vector<vector<long long>> dp(n + 1, vector<long long>(k + 1, -(1LL << 60)));
  vector<deque<long long>> min_slide1(k + 1);
  min_slide1[0].push_back(0);
  vector<deque<long long>> min_slide2(k + 1);
  min_slide2[0].push_back(0);
  dp[0][0] = 0;
  for (int i = 1; i <= n; i++) {
    sum[i] = sum[i - 1] + a[i];
    for (int j = k; j >= 1; j--) {
      while (!min_slide1[j - 1].empty() && min_slide1[j - 1].front() < i - m) {
        min_slide1[j - 1].pop_front();
      }
      if (!min_slide1[j - 1].empty()) {
        int id = min_slide1[j - 1].front();
        dp[i][j] = max(dp[i][j], dp[id][j - 1] - sum[id] + sum[i]);
      }
      while (!min_slide2[j - 1].empty() && min_slide2[j - 1].front() < i - m) {
        min_slide2[j - 1].pop_front();
      }
      if (!min_slide2[j - 1].empty()) {
        int id = min_slide2[j - 1].front();
        dp[i][j] = max(dp[i][j], dp[id][j - 1] + sum[id] - sum[i]);
      }
      while (!min_slide1[j].empty() && dp[min_slide1[j].front()][j] - sum[min_slide1[j].front()] < dp[i][j] - sum[i]) {
        min_slide1[j].pop_back();
      }
      min_slide1[j].push_back(i);
      while (!min_slide2[j].empty() && dp[min_slide2[j].front()][j] + sum[min_slide2[j].front()] < dp[i][j] + sum[i]) {
        min_slide2[j].pop_back();
      }
      min_slide2[j].push_back(i);
    }
  }
  cout << dp[n][k] << endl;
  return 0;
}