#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<ll, ll> p_ll;

template<class T>
void debug(T itr1, T itr2) { auto now = itr1; while(now<itr2) { cout << *now << " "; now++; } cout << endl; }
#define repr(i,from,to) for (ll i=(ll)from; i<(ll)to; i++)
#define all(vec) vec.begin(), vec.end()
#define rep(i,N) repr(i,0,N)
#define per(i,N) for (int i=(int)N-1; i>=0; i--)

const ll MOD = pow(10,9)+7;
const ll LLINF = pow(2,61)-1;
const int INF = pow(2,30)-1;

vector<ll> fac;
void c_fac(int x=pow(10,6)+10) { fac.resize(x,true); rep(i,x) fac[i] = i ? (fac[i-1]*i)%MOD : 1; }
ll inv(ll a, ll m=MOD) { ll b = m, x = 1, y = 0; while (b!=0) { int d = a/b; a -= b*d; swap(a,b); x -= y*d; swap(x,y); } return (x+m)%m; }
ll nck(ll n, ll k) { return fac[n]*inv(fac[k]*fac[n-k]%MOD)%MOD; }
ll gcd(ll a, ll b) { if (a<b) swap(a,b); return b==0 ? a : gcd(b, a%b); }
ll lcm(ll a, ll b) { return a/gcd(a,b)*b; }


int main() {
  ll N, K, M; cin >> N >> K >> M;
  ll A[N]; rep(i,N) cin >> A[i];
  ll sum[N+1] = {}; rep(i,N) sum[i+1] = sum[i] + A[i];

  ll dp[N+1][K+1] = {}; rep(i,N+1) rep(j,K+1) dp[i][j] = -1*LLINF; dp[0][0] = 0;
  repr(j,1,K+1) {
    deque<ll> deq1, deq2;
    repr(i,1,N+1) {
      if (deq1.size()&&deq1.front()<=(i-1)-M) deq1.pop_front();
      while (deq1.size()&&(dp[deq1.back()][j-1]-sum[deq1.back()]<dp[i-1][j-1]-sum[i-1])) deq1.pop_back();
      deq1.push_back(i-1);
      if (deq2.size()&&deq2.front()<=(i-1)-M) deq2.pop_front();
      while (deq2.size()&&(dp[deq2.back()][j-1]+sum[deq2.back()]<dp[i-1][j-1]+sum[i-1])) deq2.pop_back();
      deq2.push_back(i-1);

      dp[i][j] = max(dp[i][j], dp[deq1.front()][j-1]-sum[deq1.front()] + sum[i]);
      dp[i][j] = max(dp[i][j], dp[deq2.front()][j-1]+sum[deq2.front()] - sum[i]);
      // cout << i << "," << j << endl;
      // for (auto x: deq1) cout << x << " "; cout << endl;
    }
  }
  // rep(j,K+1) { rep(i,N+1) cout << dp[i][j] << " "; cout << endl; }

  ll result = dp[N][K];
  cout << result << endl;
  return 0;
}