#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
const int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

template <typename T>
vector<T> slide_min(const vector<T> &a, int len) {
  int n = a.size();
  vector<T> res(n - len + 1);
  deque<T> deq;
  REP(i, n) {
    while (!deq.empty() && a[deq.back()] >= a[i]) deq.pop_back();
    deq.emplace_back(i);
    if (i + 1 >= len) {
      int left = i + 1 - len;
      res[left] = a[deq.front()];
      if (deq.front() == left) deq.pop_front();
    }
  }
  return res;
}

int main() {
  int n, k, m; cin >> n >> k >> m;
  vector<int> a(n); REP(i, n) cin >> a[i];
  vector r(n + 1, 0LL), dp(n + 1, -LINF);
  for (int i = n - 1; i >= 0; --i) r[i] = r[i + 1] + a[i];
  dp[0] = 0;
  while (k--) {
    vector nx(n + 1, -LINF);
    deque<int> mn, mx;
    REP(i, n) {
      while (!mn.empty() && dp[mn.back()] - r[mn.back()] <= dp[i] - r[i]) mn.pop_back();
      mn.emplace_back(i);
      chmax(nx[i + 1], dp[mn.front()] - r[mn.front()] + r[i + 1]);
      if (mn.front() == i + 1 - m) mn.pop_front();
      while (!mx.empty() && dp[mx.back()] + r[mx.back()] <= dp[i] + r[i]) mx.pop_back();
      mx.emplace_back(i);
      chmax(nx[i + 1], dp[mx.front()] + r[mx.front()] - r[i + 1]);
      if (mx.front() == i + 1 - m) mx.pop_front();
    }
    dp.swap(nx);
    // REP(i, n + 1) cout << dp[i] << " \n"[i == n];
  }
  cout << dp[n] << '\n';
  return 0;
}