#include<bits/stdc++.h>
using namespace std;
#define rep2(i,j,k) for(ll i=ll(j); i<ll(k); i++)
#define rep(i,j) rep2(i,0,j)
#define rrep2(i,j,k) for(ll i=ll(j)-1;i>=ll(k);i--)
#define rrep(i,j) rrep2(i,j,0)
#define SZ(a) ll(a.size())
#define all(a) a.begin(),a.end()
#define eb emplace_back
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vl>;
const ll inf=LLONG_MAX/4;
template<typename T>
bool chmin(T& a,T b){return a>b?a=b,1:0;}
template<typename T>
bool chmax(T& a,T b){return a<b?a=b,1:0;}

using ld=long double;
using Pt=complex<ld>;
using vt=vector<Pt>;
const ld EPS=1e-9;
using P=pair<ll,ll>;
using vp=vector<P>;
using vvp=vector<vp>;
using F=pair<ld,ld>;

#define ln "\n"
#define r(a) real(a)
#define i(a) imag(a)

bool equal(ld a,ld b){return abs(a-b)<=EPS;}
bool equal(Pt a,Pt b){return equal(r(a),r(b)) && equal(i(a),i(b));}
ld cross(Pt a,Pt b){return r(a)*i(b)-i(a)*r(b);}
ld dot(Pt a,Pt b){return r(a)*r(b)+i(a)*i(b);}
ld cross(Pt a,Pt b,Pt c){return cross(b-a,c-a);}

Pt input(){
	ld x,y;cin>>x>>y;
	return Pt(x,y);
}

Pt tr(Pt p0,Pt p1,Pt q0,Pt q1,Pt r){
	Pt dp=p1-p0,dq=q1-q0;
	Pt num(cross(dp,dq),dot(dp,dq));
	return q0+Pt(cross(r-p0,num),dot(r-p0,num))/norm(dp);
}

int main(){
	cin.tie(0)->sync_with_stdio(0);
	cout<<fixed<<setprecision(15);
	ll n;cin>>n;
	vl m(n);
	vector<vt> p(n);
	rep(i,n){
		cin>>m[i];
		p[i].resize(m[i]);
		rep(j,m[i]) p[i][j]=input();
	}
	vector<bool> flag(n);
	vector<vt> ans(n);
	queue<ll> que;
	auto comp=[&](ld a,ld b){
		return a+EPS<b;
	};
	map<ld,vp,decltype(comp)> data{comp};
	rep(i,n){
		ans[i].resize(m[i]);
		rep(j,m[i]){
			Pt a=p[i][(j+m[i]-1)%m[i]];
			Pt b=p[i][j], c=p[i][(j+1)%m[i]];
			if(equal(dot(b-a,b-c),0)) continue;
			data[abs(b-c)].eb(i,j);
		}
	}
	rep(i,n){
		rep(j,m[i]){
			Pt a=p[i][(j+m[i]-1)%m[i]],
			b=p[i][j],
			c=p[i][(j+1)%m[i]];
			if(equal(dot(b-a,b-c),0)){
				ll nxt=i;
				rep(k,m[nxt]){
					ans[nxt][k]=tr(b,c,Pt(0,0),Pt(1,0)*abs(b-c),p[nxt][k]);
				}
				flag[i]=true;
				que.push(i);
				goto XYZ;
			}
		}
	}
	XYZ:
	while(!que.empty()){
		ll now=que.front(); que.pop();
		rep(j,m[now]){
			Pt b=p[now][j], c=p[now][(j+1)%m[now]];
			if(!data.count(abs(b-c))) continue;
			for(auto el:data[abs(b-c)]){
				if(el==make_pair(now,j)) continue;
				ll nxt=el.first;
				if(flag[nxt]) continue;	
				flag[nxt]=true;
				rep(k,m[nxt]){
					ans[nxt][k]=tr(p[nxt][el.second],p[nxt][(el.second+1)%m[nxt]],ans[now][(j+1)%m[now]],ans[now][j],p[nxt][k]);
				}
				que.push(nxt);
			}	
		}
	}
	rep(i,n){
		rep(j,m[i]) cout<<r(ans[i][j])<<" "<<i(ans[i][j])<<ln;
		cout<<ln;
	}
}