#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic pop
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  ll l;
  cin >> l;
  VI a(n);
  rep(i, n) cin >> a[i];
  vector<vector<pair<int, ll>>> to(50, vector<pair<int, ll>>(n));
  rep(i, n) {
    to[0][i] = {(i + l) % n, a[i]};
  }
  rep(k, 49) {
    rep(i, n) {
      int j = to[k][i].first;
      to[k+1][i] = {to[k][j].first, to[k][i].second + to[k][j].second};
    }
  }
  ll ans = -1e18;
  rep(i, n) {
    // i + lr >= n * m
    // r >= (n * m - i) / l
    ll r = ((ll)n * m - i + l - 1) / l;
    ll v = 0;
    int now = i;
    rrep(k, 40) {
      if (r >= (1LL << k)) {
        r -= 1LL << k;
        v += to[k][now].second;
        now = to[k][now].first;
      }
    }
    chmax(ans, v);
  }
  rep(i, n) {
    // l-1-i + lr >= n * m
    // r >= (n * m - (l-1-i)) / l
    if (l - 1 - i < 0) break;
    ll r = ((ll)n * m - (l-1-i) + l - 1) / l;
    ll v = 0;
    int now = (l - 1 - i) % n;
    rrep(k, 40) {
      if (r >= (1LL << k)) {
        r -= 1LL << k;
        v += to[k][now].second;
        now = to[k][now].first;
      }
    }
    chmax(ans, v);
  }
  cout << ans << '\n';
}