POJ 1328

 
//坐标精度是int
/*
圆心位于 
*/
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <cmath>
using namespace std; 

const int N = 1005;
typedef struct Part 
{
    int a, b;
};
Part q[N];

typedef struct Node 
{
    int left, right;
};
Node node[N];

int cmp(const void *a, const void *b)//只能返回int
{
    Part *c = (Part *)a;
    Part *d = (Part *)b;
    if(c->b == d->b)
        return c->a < d->a;
    return c->b > d->b;
}

int main()
{
    int i,j,k;
    int n, d;//d为半径
    int num = 1;
    while(cin>>n>>d, n&&d)
    {
        /*
        d<0时输出无解，却忘了发现d<0后，后面还有N行输入要“干”掉.
        */
        if(d<=0)
        {
            int a, b;
            for(i=1; i<=n; i++)
                cin>>a>>b;
            cout<<"Case "<<num++<<": "<<-1<<endl;
            continue;
        }
        int cnt = 1;
        bool flag;
        for(i=1; i<=n; i++)
        {
            cin>>node[i].left>>node[i].right;
            if(abs(node[i].right)>d)
            {
                flag = true;
            }
        }
        if(flag)
        {
            cout<<"Case "<<num++<<": "<<-1<<endl;
            continue;
        }
        
        for(i=1; i<=n; i++)
        {//圆心在下面的区间内那么就可以包括那个点 
            q[i].a = node[i].left - sqrt(1.0*(d*d - node[i].right*node[i].right));
            q[i].b = node[i].left + sqrt(1.0*(d*d - node[i].right*node[i].right));        
        }
        
        //下面是区间选点问题 
        qsort(q+1, n, sizeof(Part), cmp);
        int end = q[1].b;
        for(i=2; i<=n; i++)
        {
            if(end<q[i].a)
            {
                end = q[i].b;
                cnt++;
            }
        
        }
        cout<<"Case "<<num++<<": "<<cnt<<endl; 
    }
    return 0; 
}