#pragma GCC optimize("O2")
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdarg>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#define whlie while
#define retunr return
#define reutrn return
#define reutnr return
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define inf 1001001001
#define infLL (1LL << 61)
#define FOR(i,a,b) for(int (i)=(int)(a); (i)<(int)(b); (i)++) // [a,b)
#define rep(i,N) FOR((i), 0, (int)(N)) // [0,N)
#define FORR(i,a,b) for(int (i)=(int)(b) - 1; (i)>=(int)(a); (i)--)
#define repr(i,N) FORR((i), 0, (int)(N))
#define each(x,v) for(auto &x : v)
#define all(v) (v).begin(),(v).end()
#define sz(v) ((int)(v).size())
#define vrep(v,it) for(auto it=v.begin();it!=v.end();it++)
#define vrepr(v,it) for(auto it=v.rbegin();it!=v.rend();it++)
#define ini(...) int __VA_ARGS__; in(__VA_ARGS__)
#define inl(...) ll __VA_ARGS__; in(__VA_ARGS__)
#define inc(...) char __VA_ARGS__; in(__VA_ARGS__)
#define ins(...) string __VA_ARGS__; in(__VA_ARGS__)
#define ind(...) double __VA_ARGS__; in(__VA_ARGS__)
#define inpii(...) pii __VA_ARGS__; in(__VA_ARGS__)

#ifdef LOCAL  
  #define trc(...) do { cout << #__VA_ARGS__ << " = "; dbg_out(__VA_ARGS__);} while(0)
  #define stopif(val) assert( !(val) )
  #define trcv(v,...) do { cout << #v << " = "; vector_debug(v , ##__VA_ARGS__);cout << endl;} while(0)
#else
  #define trc(...)
  #define stopif(...)
  #define trcv(...)
#endif

using namespace std;
using ll = long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vs = vector<string>;
using vpii = vector<pii>;
using vvi = vector< vector<int> >;

struct IoSetupNya {IoSetupNya() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); cerr << fixed << setprecision(15);} } iosetupnya;

int gcd(int a, int b){if(a>b) swap(a,b); return a==0 ? b : gcd(b%a,a);} ll gcd(ll a, ll b){if(a>b) swap(a,b); return a==0 ? b : gcd(b%a,a);}
ll lcm(int a, int b){return (1LL * a / gcd(a,b)) * b;} ll lcm(ll a, ll b){return (a / gcd(a,b)) * b;}
inline ll pow(int a, int b){ll ans = 1; rep(i,b) ans *= a; return ans;} inline ll pow(ll a, ll b){ll ans = 1; rep(i,b) ans*= a; return ans;}
inline ll pow(int a, ll b){ll ans = 1; rep(i,b) ans *= a; return ans;} inline ll pow(ll a, int b){ll ans = 1; rep(i,b) ans*= a; return ans;}
template<typename T, typename U> inline bool amin(T &x, U y) { return (y < x) ? (x = y, true) : false; }
template<typename T, typename U> inline bool amax(T &x, U y) { return (x < y) ? (x = y, true) : false; }
template<typename C> inline void _cin(C &c){cin >> c;}
template<typename T,typename U> inline void _cin(pair<T,U> &p){cin >> p.fi; cin >> p.se;}
template<typename C> inline void _cout(const C &c){cout << c;}
template<typename T,typename U> inline void _cout(const pair<T,U> &p){cout << p.fi << ' ' << p.se;}
void in(){} template <typename T,class... U> void in(T &t,U &...u){ _cin(t); in(u...);}
void out(){cout << "\n";} template <typename T,class... U> void out(const T &t,U ...u){ _cout(t); if(sizeof...(u)) cout << ' '; out(u...);}
template<typename C> inline void in(vector<C> &v,int N=-1){if(sz(v) != 0){int M=(N == -1) ? sz(v) : N; rep(i,M) _cin(v[i]);}else{C c;rep(i,N) v.pb((_cin(c),c));}}
template<typename C> inline void in(C v[],int N){rep(i,N) _cin(v[i]);}
template<typename C> inline void out(const vector<C> &v,int N=-1){int M=(N == -1) ? sz(v) : N; rep(i,M) {cout<<( (i)?" ":"" ); _cout(v[i]);} cout<<"\n";}
template<typename C> inline void out(C v[],int N){rep(i,N) {cout<<( (i)?" ":"" ); _cout(v[i]);} cout<<"\n";}
template<typename C> inline void vector_debug(const vector<C> &v,int N=-1){cout << "{"; int M=(N == -1) ? sz(v) : N; rep(i,M) {cout<<( (i)?", ":"" ); _cout(v[i]);} cout<<"}";}
template<typename C> inline void vector_debug(C v[], int N){cout << "{"; rep(i,N) {cout<<((i)?", ":""); _cout(*(v+i));} cout<<"}";}
void dbg_out(){cout << endl;} template <typename T,class... U> void dbg_out(const T &t,U ...u){ _cout(t); if(sizeof...(u)) cout << ", "; dbg_out(u...);}
template<typename C,class... U> void dbg_out(const vector<C> &v,U ...u){vector_debug(v); if(sizeof...(u)) cout << ", "; dbg_out(u...);}
template<typename C,class... U> void dbg_out(const vector<vector<C>> &v,U ...u){cout << "{ "; rep(i,sz(v)) {if(i)cout<<", "; vector_debug(v[i]);} cout << " }"; if(sizeof...(u)) cout << ", "; dbg_out(u...);}
template<typename C> inline C vmax(const vector<C> &v){C n=v[0]; rep(i,sz(v)) amax(n,v[i]); return n;} template<typename C> inline C vmax(C v[], int N){C n=v[0]; rep( i , N ) amax(n,v[i]); return n;}
template<typename C> inline C vmin(const vector<C> &v){C n=v[0]; rep(i,sz(v)) amin(n,v[i]); return n;} template<typename C> inline C vmin(C v[], int N){C n=v[0]; rep( i , N ) amin(n,v[i]); return n;}
void die(string s){out(s); exit(0);}
#define rand mtrand
#define randinit() random_device seed_gen; mt19937_64 mtrand(seed_gen())

#define MOD 998244353

////////////
/// main ///
////////////

// スライド最大値/最小値 連続するK個の演算の和
// dat[i] ... 区間[ max(0 , i - K)  , i) の最大値
template<typename T, typename A, typename F, T UNIT>
struct Slide{
  vector<T> dat;
  Slide(A &v , int N , int K , F f){
    rep(i,N) trc(i,v[i]);
    dat.resize(N + 1);
    dat[0] = UNIT;
    deque<int> q;
    for(int i = 0; i < K - 1; i++){
      whlie(!q.empty() && ( f(v[i] , v[q.back()]) == v[i] ) )
        q.pop_back();
      q.push_back(i);
      dat[i + 1] = v[q.front()];
    }
    for(int i = K; i < N + 1; i++){
      T cur = v[i - 1];
      while(!q.empty() && ( f(cur , v[q.back()]) == cur) ) 
        q.pop_back();
      q.push_back(i - 1);
      dat[i] = v[q.front()];
      if(q.front() == i - K) q.pop_front();
    }
  }
};

ll dp[310][100100];

int main(){
  ini(N,M,K);
  vl v(N); in(v);
  auto f = [](ll a,ll b){return max(a , b);};
  //Slide<ll , decltype(v) , decltype(f) , -1> slide(v , N , K , f);
  //trc(slide.dat);
  rep(i,N) dp[1][i] = v[i];
  ll ans = -inf;
  for(int i = 2;i <= K; i++){
    Slide<ll,decltype(dp[i-1]),decltype(f),-1> slide(dp[i-1] , N , M , f);
    for(int j = 0; j < N ; j++){
      if(j + 1 < i) dp[i][j] = -1;
      else dp[i][j] = slide.dat[j] + v[j] * i;    
      trc(i , j , dp[i][j]);
    }
  }
  rep(i,N) amax(ans , dp[K][i]);
  out(ans);
  
}

Measured memory_bytes: 236540