#include<stdio.h>
#include<vector>
#include<algorithm>
using std::min_element;
using std::vector;

int n;

struct P{ int x,y,id; inline bool operator < (P b) const { return x==b.x?y<b.y:x<b.x; } };
vector<P> p;
struct T{ P a,b,c; };
vector<T> t;

inline long long cross(P a,P b,P c){ return (long long)(b.x-a.x)*(c.y-a.y)-(long long)(b.y-a.y)*(c.x-a.x); }
inline long long dot(P a,P b,P c){ return (long long)(b.x-a.x)*c.x+(long long)(b.y-a.y)*c.y; }

inline int min(int x,int y){ return x<y?x:y; }
inline int max(int x,int y){ return x>y?x:y; }
inline int sgn(int x){ return x>0?1:-(x<0); }
inline bool seg_cross(P a1,P b1,P a2,P b2)
{
	if(!cross(a1,b1,a2)||!cross(a1,b1,b2)||!cross(a2,b2,a1)||!cross(a2,b2,b1)) return !cross(a1,b1,a2)&&!cross(a1,b1,b2)&&sgn(max(min(a1.x,b1.x),min(a2.x,b2.x))-min(max(a1.x,b1.x),max(a2.x,b2.x)))+sgn(max(min(a1.y,b1.y),min(a2.y,b2.y))-min(max(a1.y,b1.y),max(a2.y,b2.y)))<0;
	return (cross(a1,b1,a2)>0)!=(cross(a1,b1,b2)>0)&&(cross(a2,b2,a1)>0)!=(cross(a2,b2,b1)>0);
}
inline bool check(T a,T b){ return seg_cross(a.a,a.b,b.a,b.b)||seg_cross(a.b,a.c,b.a,b.b)||seg_cross(a.a,a.c,b.a,b.b)||seg_cross(a.a,a.b,b.b,b.c)||seg_cross(a.b,a.c,b.b,b.c)||seg_cross(a.a,a.c,b.b,b.c)||seg_cross(a.a,a.b,b.a,b.c)||seg_cross(a.b,a.c,b.a,b.c)||seg_cross(a.a,a.c,b.a,b.c); }

inline long long dist2(P a,P b){ return (long long)(a.x-b.x)*(a.x-b.x)+(long long)(a.y-b.y)*(a.y-b.y); }

inline void reduce(vector<P> &in,vector<P> &out)
{
	P u=*in.begin(),v=*++in.begin();
	auto cmp1=[=](P a,P b){ return cross(v,a,b)?cross(v,a,b)>0:dist2(v,a)<dist2(v,b); };
	auto cmp2=[=](P a,P b){ return cross(v,a,b)?cross(v,a,b)<0:dist2(v,a)<dist2(v,b); };
	auto w1=min_element(out.begin(),out.end(),cmp1),w2=min_element(out.begin(),out.end(),cmp2),w=out.end();
	if(cross(u,v,*w1)<0) w=w1;
	else if(cross(u,v,*w2)>0) w=w2;
	t.push_back({u,v,*w}),in.erase(in.begin()),in.erase(in.begin()),out.erase(w);
}

inline void solve(vector<P> p)
{
	if(p.size()<3) return;
	P u=*p.begin(),v=*++p.begin();
	auto cmp1=[=](P a,P b){ return cross(v,a,b)?cross(v,a,b)>0:a.x<b.x; };
	auto cmp2=[=](P a,P b){ return cross(v,a,b)?cross(v,a,b)<0:a.x<b.x; };
	auto w1=min_element(p.begin()+2,p.end(),cmp1),w2=min_element(p.begin()+2,p.end(),cmp2),w=p.end();
	if(cross(u,v,*w1)<0) w=w1;
	else if(cross(u,v,*w2)>0) w=w2;
	else
	{
		while(n%3) p.pop_back(),n--;
		int c=p.size();
		while(!t.empty()&&3*c>2*p.size())
		{
			T i=*--t.end();
			p.push_back(i.a),p.push_back(i.b),p.push_back(i.c);
			c+=(cross(u,v,i.a)==0)+(cross(u,v,i.b)==0)+(cross(u,v,i.c)==0);
			t.pop_back();
		}
		vector<P> on,above,below;
		for(P i:p)
			if(cross(u,v,i)==0) on.push_back(i);
			else if(cross(u,v,i)>0) above.push_back(i);
			else below.push_back(i);
		while(on.size()>2*(above.size()+below.size())) on.pop_back();
		auto cmp3=[=](P a,P b){ return dot(u,v,a)<dot(u,v,b); };
		sort(on.begin(),on.end(),cmp3);
		if(on.size()==2*(above.size()+below.size()))
		{
			while(above.size()) reduce(on,above);
			while(below.size()) reduce(on,below);
		}
		else
		{
			while(on.size()>3&&above.size()) reduce(on,above);
			while(on.size()>3&&below.size()) reduce(on,below);
			vector<P> v;
			for(P i:on) v.push_back(i);
			for(P i:above) v.push_back(i);
			for(P i:below) v.push_back(i);
			bool flag=0;
			for(int i=0,j=i+1;j<6&&!flag;j++)
				for(int k=j+1;k<6&&!flag;k++)
				{
					bool b[6]={0};
					b[i]=1,b[j]=1,b[k]=1;
					int l=0,m=0,n=0;
					while(b[l]) l++;
					b[l]=1;
					while(b[m]) m++;
					b[m]=1;
					while(b[n]) n++;
					b[n]=1;
					if(cross(v[i],v[j],v[k])&&cross(v[l],v[m],v[n])&&!check({v[i],v[j],v[k]},{v[l],v[m],v[n]})) t.push_back({v[i],v[j],v[k]}),t.push_back({v[l],v[m],v[n]}),flag=1;
				}
		}
		return;
	}
	t.push_back({u,v,*w}),p.erase(w),p.erase(p.begin()),p.erase(p.begin()),solve(p);
}

int main()
{
	int _T;
	scanf("%d",&_T);
	for(int __T=1;__T<=_T;__T++)
	{
		t.clear(),p.clear();
		scanf("%d",&n);
		for(int i=1,x,y;i<=n;i++) scanf("%d%d",&x,&y),p.push_back({x,y,i});
		sort(p.begin(),p.end()),solve(p);
		printf("Case #%d: %d\n",__T,t.size());
		for(T i:t) printf("%d %d %d\n",i.a.id,i.b.id,i.c.id);
	}
	return 0;
}