Apple Orchard

#include <iostream>
#include <bits/stdc++.h>
using namespace std;

#define pb push_back
#define forn(i, n) for (int i = 0; i < n; i++)
#define ll long long
#define endl "\n"

const int N =1e5+1;
void solve()
{
   int n;
   cin>>n;
   stack<int> s;
   int a[n];
   forn(i,n)
    cin>>a[i];

   int ans=0;
   int i=0;
   for(i=0;i<n;i++)
   {
       while((!s.empty()) && (a[i]<a[s.top()]))
       {
           int top=s.top();
           s.pop();
           if(s.empty())
            ans=max(ans,a[top]*i);
           else
            ans=max(ans,a[top]*(i-s.top()-1));
       }
       s.push(i);
   }
    while(!s.empty())
    {
        int top=s.top();
        s.pop();
        if(s.empty())
            ans=max(ans,i*a[top]);

        else
            ans=max(ans,a[top]*(i-s.top()-1));
    }
    cout<<ans<<endl;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    solve();
}