#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int,int> p32;
typedef pair<ll,ll> p64;
typedef pair<double,double> pdd;
typedef vector<ll> v64;
typedef vector<int> v32;
typedef vector<vector<int> > vv32;
typedef vector<vector<ll> > vv64;
typedef vector<vector<p64> > vvp64;
typedef vector<p64> vp64;
typedef vector<p32> vp32;
ll MOD = 1791791791;
double eps = 1e-12;
#define forn(i,e) for(ll i = 0; i < e; i++)
#define forsn(i,s,e) for(ll i = s; i < e; i++)
#define rforn(i,s) for(ll i = s; i >= 0; i--)
#define rforsn(i,s,e) for(ll i = s; i >= e; i--)
#define ln "\n"
#define dbg(x) cout<<#x<<" = "<<x<<ln
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define INF 2e18
#define fast_cin() ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((ll)(x).size())

struct Point{
    ll x;
    ll y;
};

int main()
{
    fast_cin();
    ll t,n,k;
    cin >> t;
    forn(d,t){
        cin >> n >> k;
        vector<Point> v(n);
        forn(i,n){
            cin >> v[i].x >> v[i].y;
        }
        bool isCan = false;
        forn(i,n){
            bool f = true;
            forn(j,n){
                if((abs(v[i].x - v[j].x) + abs(v[i].y - v[j].y)) > k){
                    f = false;
                    break;
                }
            }
            if(f) isCan = true;
        }
        if(isCan){
            cout << 1 << ln;
        }
        else{
            cout << -1 << ln;
        }
    }
}