OJ Board

HEY, look at my code:

[c]
#include <stdio.h>
#include <math.h>
#define sqr(A) ((A)*(A))
main()
{
long n, i,xp,yp,x,y;
double r, xc, yc;

while (scanf ("%d\n",&n))
{
if (n==0) break;
scanf ("%ld %ld\n",&x,&y);
for (xc=x,yc=y,i=1;i<n;i++) {
scanf ("%ld %ld\n",&xp,&yp);
xc+=xp; yc+=yp ...