Radar Installation

#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
const int maxn = 1000;
struct X{
    double left;
    double right;
}dp[maxn];
int x[maxn],y[maxn];
bool cmp(X i,X j){
return i.left<j.left;}
int main(){
    int n,d,i, flag1 = 1;
    while(~scanf("%d%d",&n,&d)&&n&&d){
            int flag2 = 0;
            for( i = 1; i <= n ; i++){
              scanf("%d%d",&x[i],&y[i]);
              if(y[i] > d||d<0||y[i]<0)
              flag2 = 1;
             dp[i].left = x[i] - sqrt((double)(d*d-y[i]*y[i]));
             dp[i].right = x[i] + sqrt((double)(d*d-y[i]*y[i]));
            }
            if(flag2 == 1) {
                    printf("Case %d: -1\n",flag1);
                    flag1++;
            continue;}
            sort(dp+1,dp+n+1,cmp);
    int ax = 1,flag = 1;
        for(i = ax + 1; i <= n ; i++){
            if(dp[i].right < dp[ax].right){
                    ax = i;
            }
             else  if(dp[i].left > dp[ax].right){
                ax = i;
                flag++;
              }
          }
        printf("Case %d: %d\n",flag1,flag);
        flag1++;
     }
    return 0;
}