#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001

vector<pair<int,int>> get(vector<pair<int,int>> xy,int f){
	if(xy.size()<=2)return xy;
	vector<pair<int,int>> ret;
	vector<pair<int,int>> A;
	vector<pair<int,int>> B;
	
	if(f==0){
		sort(xy.begin(),xy.end());
		
	}
	else{
		sort(xy.begin(),xy.end(),[&](pair<int,int> a,pair<int,int> b){
			return make_pair(a.second,a.first)<make_pair(b.second,b.first);
		});
	}
	rep(i,xy.size()){
		if(i<xy.size()/2)A.push_back(xy[i]);
		else B.push_back(xy[i]);
	}
	
	
	{
		auto r = get(A,f^1);
		rep(i,r.size())ret.push_back(r[i]);
	}
	{
		auto r = get(B,f^1);
		rep(i,r.size())ret.push_back(r[i]);
	}

	return ret;
}

int main(){
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int _t;
	cin>>_t;
	
	rep(_,_t){
		int N,L;
		cin>>N>>L;
		
		vector<pair<int,int>> x(N);
		rep(i,N){
			cin>>x[i].first>>x[i].second;
		}
		auto ans = get(x,0);
		cout<<N<<endl;
		rep(i,N){
			cout<<ans[i].first<<' '<<ans[i].second<<endl;
		}
	}
	
	return 0;
}