#pragma GCC optimize ("Ofast")
#include<bits/stdc++.h>
using namespace std;
inline void rd(int &x){
  int k;
  int m=0;
  x=0;
  for(;;){
    k = getchar_unlocked();
    if(k=='-'){
      m=1;
      break;
    }
    if('0'<=k&&k<='9'){
      x=k-'0';
      break;
    }
  }
  for(;;){
    k = getchar_unlocked();
    if(k<'0'||k>'9'){
      break;
    }
    x=x*10+k-'0';
  }
  if(m){
    x=-x;
  }
}
inline void wt_L(char a){
  putchar_unlocked(a);
}
inline void wt_L(long long x){
  int s=0;
  int m=0;
  char f[20];
  if(x<0){
    m=1;
    x=-x;
  }
  while(x){
    f[s++]=x%10;
    x/=10;
  }
  if(!s){
    f[s++]=0;
  }
  if(m){
    putchar_unlocked('-');
  }
  while(s--){
    putchar_unlocked(f[s]+'0');
  }
}
template<class S, class T> inline S chmax(S &a, T b){
  if(a<b){
    a=b;
  }
  return a;
}
int N;
int A[10000];
int arr[10000];
long long lf[10001];
long long rg[10001];
int main(){
  int K;
  int mx;
  long long res = 0;
  rd(N);
  {
    int Lj4PdHRW;
    for(Lj4PdHRW=(0);Lj4PdHRW<(N);Lj4PdHRW++){
      rd(A[Lj4PdHRW]);
    }
  }
  int KL2GvlyY = N+1;
  for(K=(1);K<(KL2GvlyY);K++){
    int i;
    mx = N / K;
    for(i=(0);i<(mx);i++){
      int j;
      for(j=(0);j<(K);j++){
        arr[j] = A[i*K+j];
      }
      nth_element(arr, arr+(K-1)/2, arr+K);
      lf[i+1] = lf[i] + (long long) K * arr[(K-1)/2];
    }
    for(i=(0);i<(mx);i++){
      int j;
      for(j=(0);j<(K);j++){
        arr[j] = A[N-1-(i*K+j)];
      }
      nth_element(arr, arr+(K-1)/2, arr+K);
      rg[i+1] = rg[i] + (long long) K * arr[(K-1)/2];
    }
    for(i=(0);i<(mx);i++){
      chmax(lf[i+1], lf[i]);
    }
    for(i=(0);i<(mx);i++){
      chmax(rg[i+1], rg[i]);
    }
    for(i=(0);i<(mx+1);i++){
      chmax(res, lf[i] + rg[mx-i]);
    }
  }
  wt_L(res);
  wt_L('\n');
  return 0;
}
// cLay varsion 20191102-1

// --- original code ---
// int N, A[1d4];
// int arr[1d4];
// ll lf[10001], rg[10001];
// {
//   int mx;
//   ll res = 0;
//   rd(N,A(N));
// 
//   REP(K,1,N+1){
//     mx = N / K;
//     rep(i,mx){
//       rep(j,K) arr[j] = A[i*K+j];
//       nth_element(arr, arr+(K-1)/2, arr+K);
//       lf[i+1] = lf[i] + (ll) K * arr[(K-1)/2];
//     }
//     rep(i,mx){
//       rep(j,K) arr[j] = A[N-1-(i*K+j)];
//       nth_element(arr, arr+(K-1)/2, arr+K);
//       rg[i+1] = rg[i] + (ll) K * arr[(K-1)/2];
//     }
//     rep(i,mx) lf[i+1] >?= lf[i];
//     rep(i,mx) rg[i+1] >?= rg[i];
//     rep(i,mx+1) res >?= lf[i] + rg[mx-i];
//   }
//   wt(res);
// }