#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;
typedef long long ll;
struct player
{
	ll pw,x,y;
}p[50050];
ll n,sum=0,m,ax,ay,ans=0;
inline bool cmp1(const player &a,const player &b)
{
	return a.x<b.x;
}
inline bool cmp2(const player &a,const player &b)
{
	return a.y<b.y;
}
int main()
{
	freopen("ballc.in","r",stdin);
	freopen("ballc.out","w",stdout);
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>p[i].pw;
		sum+=p[i].pw;
	}
	for(int i=1;i<=n;i++)
	{
		cin>>p[i].x>>p[i].y;
	}
	sort(p+1,p+n+1,cmp1);
	m=0;
	for(int i=1;i<=n;i++)
	{
		m+=p[i].pw;
		if(m>sum/2)
		{
			ax=p[i].x;
			break;
		}
	}
	m=0;
	sort(p+1,p+n+1,cmp2);
	for(int i=1;i<=n;i++)
	{
		m+=p[i].pw;
		if(m>sum/2)
		{
			ay=p[i].y;
			break;
		}
	}
	for(int i=1;i<=n;i++)
		ans+=(abs(p[i].x-ax)+abs(p[i].y-ay))*p[i].pw;
	printf("%lld.00\n",ans);
	return 0;
}