gistfile1.c

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
typedef struct
{
	int x;
	int y;
}TPoint;

int cmp(TPoint a, TPoint b)
{
	if (a.x != b.x)
	return a.x > b.x;
	else return a.y < b.y;
}
int main()
{
	freopen("data.txt","r",stdin);
	int n, dis;
	TPoint h[1005];
	int ans, t = 0;
	int i, j;
	double x, l, r;
	while (scanf("%d%d",&n, &dis) &&  n && ++t)
	{
		for (i = 0; i < n; i++)
			scanf("%d%d",&h[i].x, &h[i].y);
		sort(h, h + n, cmp);
		if (h[0].y > dis) 
		{
			printf("Case %d: -1\n", t);
			continue;
		}
		x =  -sqrt(dis*dis - h[0].y*h[0].y) + h[0].x;
		ans = 1;
		for (i = 1; i < n; i++)
		{
			if (h[i].y > dis) break;
			l = -sqrt(dis*dis - h[i].y*h[i].y) + h[i].x;
			r = sqrt(dis*dis - h[i].y*h[i].y) + h[i].x;
		//	printf("l = %lf, r = %lf, x = %lf\n", l, r, x);
			if (r < x)
			{
				ans++;
				x = l;
			}
		}
		if (i != n) printf("Case %d: -1\n", t);
		else printf("Case %d: %d\n", t, ans);
	}
	return 0;
}