Description：

Solution：

Code：

#include<algorithm>

#include<iostream>

#include<cstdlib>

#include<cstdio>

#include<cmath>

#include<cctype>

#include<cstring>

using namespace std;

int n;

#define MAXN 4010

struct point

{

	double x,y;

}p[MAXN];

bool cmp_x(point a,point b){return a.x < b.x;}

bool equal(double a,double b){return (fabs(a - b) <= 1e-8);}

point top[MAXN],bot[MAXN];

int topc = 0,botc = 0;

double slope(point a,point b){return (a.y - b.y) / (a.x - b.x);}

double area(double a,double b,double c)

{

	double p = (a + b + c) / 2;

	return sqrt(p * (p - a) * (p - b) * (p - c));

}

double dis(point a,point b){return sqrt((a.x - b.x) * (a.x - b.x) + (a.y - b.y) * (a.y - b.y));}

double calc(point p1,point p2,point p3,point p4)

{

	return area(dis(p1,p3),dis(p1,p2),dis(p2,p3)) + area(dis(p1,p4),dis(p3,p4),dis(p1,p3));

}

int main()

{

	scanf("%d",&n);

	for(int i = 1;i <= n;++i)scanf("%lf%lf",&p[i].x,&p[i].y);

	sort(p + 1,p + 1 + n,cmp_x);

	for(int i = 1;i <= n;++i)

	{

		if(topc == 0){top[++topc] = p[i];continue;}

		if(equal(p[i].x,top[topc].x)){if(p[i].y < top[topc].y)continue;else --topc;}

		while(topc >= 2 && slope(top[topc],p[i]) >= slope(top[topc],top[topc - 1]))--topc;

		top[++topc] = p[i];

	}

	for(int i = 1;i <= n;++i)

	{

		if(botc == 0){bot[++botc] = p[i];continue;}

		if(equal(p[i].x,bot[botc].x)){if(p[i].y > bot[botc].y)continue;else --botc;}

		while(botc >= 2 && slope(bot[botc],p[i]) <= slope(bot[botc],bot[botc - 1]))--botc;

		bot[++botc] = p[i];

	}

	if(!equal(bot[botc].y,top[topc].y))top[++topc] = bot[botc];

	for(int i = botc - 1;i >= 2;--i)top[++topc] = bot[i];

	if(bot[1].y != top[1].y)top[++topc] = bot[1];

	for(int i = 1;i <= topc;++i)top[i + topc] = top[i];

	for(int i = 1;i <= 2 * topc;++i)p[i] = top[i];

	double ans = 0;

	for(int i = 1;i <= topc;++i)

	{

		int cur1 = i + 1,cur2 = i + 3;

		for(int j = i + 2;j <= i + topc - 2;++j)

		{

			while(cur1 + 1 <= j && calc(p[cur1 + 1],p[i],p[cur2],p[j]) > calc(p[cur1],p[i],p[cur2],p[j]))++cur1;

			while(cur2 + 1 < i + topc && calc(p[cur1],p[i],p[cur2 + 1],p[j]) > calc(p[cur1],p[i],p[cur2],p[j]))++cur2;

			ans = max(ans,calc(p[cur1],p[i],p[cur2],p[j]));

		}

	}

	printf("%.3lf\n",ans);

	return 0;

}