#include <bits/stdc++.h>
#define ll long long
#define REP(i, n) for (ll i = 0, max_i = (n); i < max_i; i++)
#define REPI(i, a, b) for (ll i = (a), max_i = (b); i < max_i; i++)
#define ALL(obj) (obj).begin(), (obj).end()
#define RALL(obj) (obj).rbegin(), (obj).rend()
#define fi first
#define se second
#define pb push_back
#define debug(x) cerr << #x << ": " << (x) << endl
#define debug2(x, y) cerr << #x << ": " << (x) << " " << #y << ": " << y << endl;
#define int long long
using namespace std;
using II = pair<int, int>;
using VII = vector<II>;
using VI = vector<int>;
using VVI = vector<VI>;
using VVVI = vector<VVI>;
template <class T = int> inline T in() { T x; cin >> x; return x; }
template <class T = int> inline bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template <class T = int> inline bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }
template <class T> ostream& operator<<(ostream &s, const vector<T>& d) { int n = d.size(); REP (i, n) s << d[i] << " "; return s; }
template <class T> ostream& operator<<(ostream &s, const vector<vector<T>>& dd) { for (vector<T> d: dd) s << d << endl; return s; }
struct Fast { Fast() { cin.tie(0); ios::sync_with_stdio(false); } } fast;
const int MOD = 1e9 + 7;
template <class T = int>
class SegTree {
using VT = vector<T>;
int orig_n;
// k番目のノードの[l, r)について[a, b)を求める
T query(int a, int b, int k, int l, int r) {
if (r <= a || b <= l) { return UNIT; }
if (a <= l && r <= b) { return dat[k]; }
T vl = query(a, b, k * 2 + 1, l, (l + r) / 2);
T vr = query(a, b, k * 2 + 2, (l + r) / 2, r);
return f(vl, vr);
}
public:
int N;
VT dat;
function<T(T, T)> f;
T UNIT;
SegTree() {}
SegTree(int n, function<T(T, T)> f_, const T unit) : orig_n(n), f(f_), UNIT(unit) {
for (N = 1; N < n; N *= 2);
dat = VT(2 * N - 1, UNIT);
}
SegTree(const VT& a, function<T(T, T)> f_ = [](int a, int b) { return min(a, b); }, T unit = 1e15)
: orig_n(a.size()), f(f_), UNIT(unit) {
for (N = 1; N < a.size(); N *= 2);
dat = VT(2 * N - 1);
REP (i, a.size()) {
dat[N - 1 + i] = a[i];
}
for (int k = N - 2; k >= 0; k--) {
dat[k] = f(dat[2 * k + 1], dat[2 * k + 2]);
}
}
// k番目をaに
void update(int k, int a) {
k += N - 1;
dat[k] = a;
while (k > 0) {
k = (k - 1) / 2;
dat[k] = f(dat[2 * k + 1], dat[2 * k + 2]);
}
}
// [a, b)でのクエリ
T query(int a, int b) {
assert(0 <= a && a < b && b <= orig_n);
return query(a, b, 0, 0, N);
}
};
signed main() {
int N, M, K; cin >> N >> M >> K;
VI A(N);
REP (i, N) cin >> A[i];
auto f = [](int a, int b) { return max(a, b); };
vector<SegTree<>> sts(K + 1, SegTree<>(N + 1, f, 0));
REPI (i, 1, K + 1) {
REPI (j, 1, N + 1) {
int bef = sts[i - 1].query(max(0ll, j - M), j);
sts[i].update(j, bef + i * A[j - 1]);
}
}
cout << sts[K].query(0, N + 1) << endl;
}