#include<bits/stdc++.h>
using namespace std;
pair<double,double> a[15001];
int main()
{
    freopen("sprinkler.in","r",stdin);
    freopen("sprinkler.out","w",stdout);
    int T, n;
    double L, W;
    cin >> T;
    for(int i = 1; i <= T; ++i)
    {
        cin >> n>> L >> W;
        W=W/2.0;
        for(int j=1;j<=n;++j)
        {
            double d,b;
            cin>>d>>b;
            double c=0;
            if(b*b>W*W)
            {
            c=sqrt(b*b-W*W);
            a[j].first=d-c;
            a[j].second=d+c;
            if(a[j].first<0) a[j].first=0;
            if(a[j].second>L) a[j].second=L;
        }
        else 
        {
            j--;
            n--;
        }
    }
    sort(a+1,a+1+n);
    int tot=0,r=0;
    double p=0;
    while(p<=L)
      {
        if(p==L)
        {
            cout<<tot<<endl;
            break;
        }
        bool flag=true;
        for(int j=r+1;j<=n;++j)
        {
            if(a[j].first<=p)
            {
                flag=false;
                r=j;
            }
        }          
        p=a[r].second;
        tot++;
        if(flag==true) 
        {
            cout<<-1<<endl;
            break;
        }
      }
    }
    return 0;
}