C++ :

#include <cstdio>
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <vector>
#include <deque>

using namespace std ;
int n,i,j,l,r,a[100002],q[100002],ll[100002],rr[100002];
long long maxn,s[100002];
int main()
{
	//freopen("feelgood.in","r",stdin);
	//freopen("feelgood.out","w",stdout);
	cin>>n;
	for(i=1;i<=n;i++)
	{
		cin>>a[i];
		s[i]=s[i-1]+a[i];
	}
	l=1;r=0;
	memset(ll,0,sizeof(ll));
	memset(rr,0,sizeof(rr));
	memset(q,0,sizeof(q));
	for(i=1;i<=n+1;i++)
	{
		while(a[i]<a[q[r]]&&l<=r)
			rr[q[r--]]=i-1;
	    q[++r]=i;
	}
	l=1;r=0;
	memset(q,0,sizeof(q));
	for(i=n;i>=0;i--)
	{
		while(a[i]<a[q[r]]&&l<=r)
			ll[q[r--]]=i+1;
		q[++r]=i;
	}
	maxn=0;
	for(i=1;i<=n;i++)
	  if((s[rr[i]]-s[ll[i]-1])*a[i]>maxn)
	    maxn=(s[rr[i]]-s[ll[i]-1])*a[i];
	cout<<maxn;
}