#include<bits/stdc++.h>
using namespace std;
//#pragma GCC optimize("Ofast")

#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define vtpl(x,y,z) vector<tuple<x,y,z>>
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[9]={1,0,-1,0,1,1,-1,-1,0};
const ll dx[9]={0,1,0,-1,1,-1,1,-1,0};
template<class T> inline bool chmin(T& a, T b) {
    if (a >= b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}


  const int logn = 30;//nに合わせて調整
  const int maxn = 1 << logn;
 
  long long hilbertorder(int x, int y) {//ここはllじゃないといけない
    long long  d = 0;
    for (int s = 1<<logn-1; s; s >>= 1) {
        bool rx = x & s, ry = y & s;
        d = d << 2 | rx * 3 ^ static_cast<int>(ry);
        if (ry) continue;
		if (rx) {
			x = maxn - x;
			y = maxn - y;
		}
		swap(x, y);
    }
    return d;
  }


int main(){
    ll t;cin >> t;
    while(t--){
        ll n;cin >> n;
        ll l;cin >> l;
        vector<int> x(n),y(n);
        vl ord(n);rep(i,n)cin >> x[i] >> y[i];
        rep(i,n)ord[i]=i;
        sort(all(ord),[&](int a,int b){return hilbertorder(x[a],y[a])<hilbertorder(x[b],y[b]);});
        cout << n << endl;
        rep(i,n){
            cout << x[ord[i]] <<" " << y[ord[i]] << endl;
        }

    }
}