POJ 1328

#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
struct island
{
  double r,l;
};
bool cmp(island a,island b)
{
  return a.l<b.l;
}
int main()
{
  int n,r,k=0;
  double x,y;
  island p[1005];
  while(cin>>n>>r &&(n||r))
    {
      int err=0;
      int rr=r*r;
      for(int i=0; i<n; i++)
        {
          cin>>x>>y;
          if(fabs(y)>r)
            {
              err=1;
              //break;
            }
          p[i].l=x-sqrt(rr-y*y);
          p[i].r=x+sqrt(rr-y*y);
        }
      cout<<"Case "<<++k<<": ";
      if(err)
        {
          cout<<"-1"<<endl;
          continue;
        }
      sort(p,p+n,cmp);
      double now=p[0].r;
      int ans=1;
      for(int i=1; i<n; i++)
        {
          if(now>p[i].r) now=p[i].r;
          else if(now<p[i].l)
            {
              ans++;
              now=p[i].r;
            }
        }
      cout<<ans<<endl;
    }
  return 0;
}