#include<bits/stdc++.h>
using namespace std;

const int maxn=600005;
const int mlog=21;
int T,n,m,ql,qr;
int l[maxn],r[maxn],ord[maxn],mn[maxn],mx[maxn],pre[maxn],sum[maxn];
int par[maxn][mlog],que[maxn];
vector<int>all,pos;
bool cmp(int a,int b){
	return r[a]<r[b];
}

int main(){
	scanf("%d",&T);
	while(T--){
		scanf("%d",&n);
		all.clear();
		for(int i=0;i<n;i++){
			scanf("%d%d",&l[i],&r[i]);
			all.push_back(l[i]-1);
			all.push_back(l[i]);
			all.push_back(l[i]+1);
			all.push_back(r[i]-1);
			all.push_back(r[i]);
			all.push_back(r[i]+1);
		}
		sort(all.begin(),all.end());
		all.resize(unique(all.begin(),all.end())-all.begin());
		m=int(all.size());
		for(int i=0;i<m;i++)mn[i]=m,mx[i]=-1,sum[i]=0;
		for(int i=0;i<n;i++){
			l[i]=lower_bound(all.begin(),all.end(),l[i])-all.begin();
			r[i]=lower_bound(all.begin(),all.end(),r[i])-all.begin();
			mn[l[i]]=min(mn[l[i]],r[i]);
			mx[l[i]]=max(mx[l[i]],r[i]);
			ord[i]=i;
		}
		sort(ord,ord+n,cmp);
		int last=-1;
		pos.clear();
		for(int i=0;i<n;i++)if(l[ord[i]]>last){
			pos.push_back(r[ord[i]]);
			sum[r[ord[i]]]++;
			last=r[ord[i]];
		}
		for(int i=0;i<m;i++){
			pre[i]=max(!i?-1:pre[i-1],mx[i]);
			sum[i]=(!i?0:sum[i-1])+sum[i];
			for(int j=0;j<mlog;j++)par[i][j]=-1;
		}
		int ans=0;
		for(int i=0;i<n;i++)ans=max(ans,sum[r[i]]-(!l[i]?0:sum[l[i]-1]));
		ql=qr=0;
		int cur=m;
		for(int i=m-1;i>=0;i--){
			bool ok=true;
			if(cur==m)par[i][0]=-1;
			else if(ql<qr)par[i][0]=que[ql];
			else ok=false;
			if(ok){
				for(int j=1;j<mlog;j++){
					if(par[i][j-1]<0)par[i][j]=-1;
					else par[i][j]=par[par[i][j-1]][j-1];
				}
				int x=i;
				for(int j=mlog-1;j>=0;j--)if(x>=0&&(((ans-1)>>j)&1))
					x=par[x][j];
				if(x>=0&&pre[i]>=x)ok=false;
			}
			if(ok){
				que[qr++]=i;
				if(i<=pos[0]){
					ans--;
					pos.clear();
					for(int j=i;j>=0;j=par[j][0])pos.push_back(j);
					break;
				}
			}
			cur=min(cur,mn[i]);
			while(ql<qr&&que[ql]>cur)ql++;
		}
		printf("%d %d",ans,int(pos.size()));
		for(int i=0;i<int(pos.size());i++)printf(" %d",all[pos[i]]);
		puts("");
	}
	return 0;
}