#include <fstream>
#include <algorithm>
#include <string.h>
#define NMax 2010
#define INF 1000000
using namespace std;
ifstream f("camera.in");
ofstream g("camera.out");
struct Point {
double x;
double y;
Point() {};
Point(double _x, double _y) {
x = _x;
y = _y;
}
} polyg[NMax], crt[NMax], nex[NMax];
int n, nP, newNP;
int det(Point p1, Point p2, Point p3)
{
return p1.x*p2.y + p2.x*p3.y + p3.x*p1.y - p3.x*p2.y - p1.x*p3.y - p2.x*p1.y;
}
double area_sign(Point p1, Point p2)
{
return p1.x*p2.y - p2.x*p1.y;
}
Point get_intersection_coords(Point p1, Point p2, Point p3, Point p4)
{
double a1 = p2.y - p1.y;
double b1 = p1.x - p2.x;
double c1 = p1.y*p2.x - p1.x*p2.y;
double a2 = p4.y - p3.y;
double b2 = p3.x - p4.x;
double c2 = p3.y*p4.x - p3.x*p4.y;
Point answ;
answ.x = (b2*c1 - b1*c2) / (a1*b2 - a2*b1);
answ.y = (a1*c2 - a2*c1) / (a1*b2 - a2*b1);
return answ;
}
int dist(Point p1, Point p2)
{
return (p1.x - p2.x)*(p1.x - p2.x) + (p1.y - p2.y)*(p1.y - p2.y);
}
bool intersect(Point p1, Point p2, Point p3, Point p4)
{
double d1 = det(p1, p3, p2);
double d2 = det(p1, p4, p2);
double d3 = det(p3, p1, p4);
double d4 = det(p3, p2, p4);
if (d1*d2 < 0 || d3*d4 < 0)
return true;
return false;
}
int main()
{
f >> n;
Point leftCorner(INF, INF), rightCorner(0, 0);
for (int i = 1; i <= n; i++) {
f >> polyg[i].x >> polyg[i].y;
if (leftCorner.x > polyg[i].x)
leftCorner.x = polyg[i].x;
if (leftCorner.y > polyg[i].y)
leftCorner.y = polyg[i].y;
if (rightCorner.x < polyg[i].x)
rightCorner.x = polyg[i].x;
if (rightCorner.y < polyg[i].y)
rightCorner.y = polyg[i].y;
}
crt[++nP] = Point(leftCorner.x, leftCorner.y);
crt[++nP] = Point(rightCorner.x, leftCorner.y);
crt[++nP] = Point(rightCorner.x, rightCorner.y);
crt[++nP] = Point(rightCorner.x, leftCorner.y);
for (int i = 1; i <= n; i++) {
for (int j = i + 1; j <= n; j++) {
double sgn = area_sign(polyg[i], polyg[j]);
if (sgn < 0)
swap(polyg[i], polyg[j]);
else if (sgn == 0) {
double di = dist(Point(0, 0), polyg[i]);
double dj = dist(Point(0, 0), polyg[j]);
if (di == 0) //sar peste (0, 0)
continue;
if (polyg[i].y == 0 && polyg[j].y == 0) {
if (di > dj)
swap(polyg[i], polyg[j]);
}
else if (di < dj)
swap(polyg[i], polyg[j]);
}
}
}
polyg[n + 1] = polyg[1];
crt[nP + 1] = crt[1];
//inchid answ sau nu?
for (int i = 1; i <= n; i++) { //pol edges
Point p1 = polyg[i];
Point p2 = polyg[i + 1];
for (int j = 1; j <= nP; j++) { //answ edg
Point p3 = crt[j];
Point p4 = crt[j + 1];
if (intersect(p1, p2, p3, p4) == true) {
Point intersection = get_intersection_coords(p1, p2, p3, p4);
if (det(p1, p2, p4) < 0) { // ce se intampla cand loveste colt din answ
nex[++newNP] = intersection;
nex[++newNP] = p4;
}
else
nex[++newNP] = intersection;
}
else {
if (det(p1, p2, p3) <= 0)
nex[++newNP] = p3;
if (det(p1, p2, p4) <= 0)
nex[++newNP] = p4;
}
}
nP = newNP;
newNP = 0;
swap(crt, nex);
memset(nex, 0, sizeof(nex));
}
return 0;
}