Here is my source.I am using VStudio 6.0 an dit is OK but...I got
Compilation Error. How to understand why and what to compile my
program with????

#include <stdio.h>
long ind,pom,n,x[10000],y[10000],ymin,i,j,xx,yy;
int pos[10000];
void main()
{
    scanf("%ld",&n);
    ymin=1000000000;
    for (i=0;i<n;i++)
    {
        scanf("%ld%ld",&x[i],&y[i]);
        pos[i]=i;
        if (ymin>y[i])
        {
            ind=i;
            ymin=y[i];
        }
    }
    pom=y[ind];
    y[ind]=y[n-1];
    y[n-1]=pom;
    pom=x[ind];
    x[ind]=x[n-1];
    x[n-1]=pom;
    xx=x[n-1];
    yy=y[n-1];
    pos[ind]=n-1;
    pos[n-1]=ind;
    for(i=0;i<n-1;i++)
        for(j=i+1;j<n;j++)
            if (((float)(x[i]-xx)*(float)(y[j]-yy))-
                ((float)(x[j]-xx)*(float)(y[i]-yy))>0)
            {
                pom=y[i];
                y[i]=y[j];
                y[j]=pom;
                pom=x[i];
                x[i]=x[j];
                x[j]=pom;
                pom=(long)pos[i];
                pos[i]=pos[j];
                pos[j]=(int)pom;
            }
printf("%d %d\n",pos[n-1]+1,pos[(int)((n/2)-1)]+1);
}