mycode:
#include<stdio.h>
#include<math.h>
#include<algorithm>
using namespace std;
#define N 10002
struct node
{
    double  x,y;
    int num;
}point[N];
int n;
int cmp(node a,node b)
{
    double pp=atan2(a.y-point[0].y,a.x-point[0].x);
    double qq=atan2(b.y-point[0].y,b.x-point[0].x);
    //double pp=(a.x-point[0].x)*(b.y-point[0].y)-(a.y-point[0].y)*(b.x-point[0].x);
    return pp>qq;
}
int main()
{
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        scanf("%lf%lf",&point[i].x,&point[i].y);
        point[i].num=i+1;
    }
    int pos=0;
    /*for(int i=1;i<n;i++)
    {
        if(point[i].x<point[pos].x||(point[i].x==point[pos].x)&&point[i].y<point[pos].y)
        pos=i;
    }
    swap(point[0],point[pos]);*/
    sort(point+1,point+n,cmp);
    printf("%d %d\n",point[0].num ,point[n/2].num);
    return 0;
}
what it`s function in /*  */