#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

int max(int a,int b)
{
    if(a>b)
    {
        return a;
    }
    else
    {
        return b;
    }
}
int find(int i,int k,int n)
{
    int x=0;
    for(int l=1;l<=k-1;l++)
    {
        x+=n;
        n--;
    }
    x=x+i;
    return x;
}
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n,j,t=0,s=0;
    cin>>n;
    int a[n],b[(n*(n+1))/2];
    for(int y=0;y<n;y++)
    {
        cin>>a[y];
    }
    for(int k=0;k<=n-1;k++)
    {
        for(int i=0;i<=n-k-1;i++)
        {
            if(k==0)
            {
                b[t]=a[i];
            }
            else
            {
                b[t]=max(b[find(i,k,n)],a[i+k]);
            }
            t++;
        }
    }
    t=0;
    int g=(n*(n+1))/2;
    int d=(g*(g+1))/2;
    int c[d];
    for(int f=0;f<=g-1;f++)
    {
        for(int q=0;q<=g-f-1;q++)
        {
            if(f==0)
            {
                c[t]=b[q];
            }
            else
            {
                c[t]=max(c[find(q,f,g)],b[f+q]);
            }
            s+=c[t];
            t++;
        }
    }
    cout<<s;
    return 0;
}