poj 2007 Scrambled Polygon

#include<stdio.h>
#include<algorithm>
using namespace std;
#define Max 60
struct Point
{
    int x,y;
} p[Max];
int xmult(Point p1,Point p2,Point p0)
{
    return (p1.x-p0.x)*(p2.y-p0.y)-(p2.x-p0.x)*(p1.y-p0.y);
}
int pos;
bool cmp(Point p1,Point p2)
{
    if(xmult(p1,p2,p[pos])>0)
        return true;
    return false;
}
int main()
{
    int i,n=0;
    while(scanf("%d%d",&p[n].x,&p[n].y)!=EOF)
    {
        n++;
        //if(n==6)break;
    }
    for(i=1; i<n; i++)
    {
        pos=i-1;
        sort(p+i,p+n,cmp);
    }
    for(i=0; i<n; i++)
        printf("(%d,%d)\n",p[i].x,p[i].y);
    return 0;
}