#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
#define MAX_N 1005

#define rep(i, s, e) for(int i = (s);i < (e);i++)
#define repEqual(i, s, e) for(int i = (s);i <= (e);i++)
#define repZero(i, e) for(int i = 0;i < (e);i++)
#define mem(a,val) memset(a,val,sizeof a)

const ll INF = (long long)2e9;
const ll mod = (long long)1e7 + 19;

//----------START---------------------------
vector<int> maxTransform(vector<int> arr)
{
    std::vector<int> b;
    int len = arr.size();

    repZero(k,len){
        repZero(i,len-k){
            int Max=0,j= i+k;
            repEqual(temp,i,j)
                Max = max(Max,arr[temp]);

            b.push_back(Max);
        }
    }
    return b;

}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);

  int n;
  cin>>n;
  
  ll result = 0;
  std::vector<int> arr(n);
  repZero(i,n)
    cin>>arr[i];
  
  std::vector<int> ans1 = maxTransform(arr);
  std::vector<int> ans2 = maxTransform(ans1);

  repZero(i,ans2.size())
    result += ans2[i];

  cout<<result<<"\n";
  
  
  return 0;
}