#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>

using namespace std;

int n;

struct pointt
{
	int w,x,y;
}P[5000001];

int cmp(const void *a,const void *b)
{
	pointt *aa=(pointt *)a;
	pointt *bb=(pointt *)b;
	return aa->x - bb->x;
}

int solve()
{
	qsort(P+1,n,sizeof(P[0]),cmp);
	int cost=0;int q=P[1].w;int h=0;
	for (int i=2;i<=n;i++)
	{
		cost+=(P[i].x-P[1].x)*P[i].w;
		h+=P[i].w;
	}
	int re=cost;
	for (int i=2;i<=n;i++)
	{
		cost+=(P[i].x-P[i-1].x)*q;
		cost-=(P[i].x-P[i-1].x)*h;
		q+=P[i].w;
		h-=P[i].w;
		if (cost<re) re=cost;
	}
	return re;
}

int main()
{
	freopen("ballc.in","r",stdin);
	freopen("ballc.out","w",stdout);
	scanf("%d",&n);
	for (int i=1;i<=n;i++)
	scanf("%d",&P[i].w);
	for (int i=1;i<=n;i++)
	scanf("%d%d",&P[i].x,&P[i].y);
	int ans=solve();
	for (int i=1;i<=n;i++)
	swap(P[i].x,P[i].y);
	ans+=solve();
	printf("%d.00\n",ans);
	return 0;
}