#include <bits/stdc++.h>
using namespace std;
const int LOG = 50;
const long long INF = 2000000000000000000;
int main(){
  int N, M;
  long long L;
  cin >> N >> M >> L;
  vector<int> A(N);
  for (int i = 0; i < N; i++){
    cin >> A[i];
  }
  vector<vector<int>> nxt(LOG, vector<int>(N, 0));
  vector<vector<long long>> sum(LOG, vector<long long>(N, 0));
  for (int i = 0; i < N; i++){
    nxt[0][i] = (i + L) % N;
    sum[0][i] = A[i];
  }
  for (int i = 0; i < LOG - 1; i++){
    for (int j = 0; j < N; j++){
      nxt[i + 1][j] = nxt[i][nxt[i][j]];
      sum[i + 1][j] = sum[i][j] + sum[i][nxt[i][j]];
    }
  }
  vector<long long> a(N, 0), b(N, 0);
  for (int i = 0; i < N; i++){
    long long R = (long long) N * M / L;
    int p = i;
    for (int j = 0; j < LOG; j++){
      if ((R >> j & 1) == 1){
        a[i] += sum[j][p];
        p = nxt[j][p];
      }
    }
  }
  for (int i = 0; i < N; i++){
    long long R = (long long) N * M / L + 1;
    int p = i;
    for (int j = 0; j < LOG; j++){
      if ((R >> j & 1) == 1){
        b[i] += sum[j][p];
        p = nxt[j][p];
      }
    }
  }
  long long r = (long long) M * N % L;
  long long ans = -INF;
  for (int i = 0; i < min(r, (long long) N); i++){
    ans = max(ans, b[i]);
  }
  for (long long i = max(r, L - N); i < L; i++){
    ans = max(ans, a[i % N]);
  }
  cout << ans << endl;
}