//Author: Kevin
#include<bits/stdc++.h>
//#pragma GCC optimize("O2")
using namespace std;
#define ll long long
#define ull unsigned ll
#define ld long double
#define pb emplace_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
#define inf 0x3f3f3f3f
#define pii pair<int,int>
#define lb(v,x) (int)(lower_bound(ALL(v),x)-v.begin())
#define ub(v,x) (int)(upper_bound(ALL(v),x)-v.begin())
#define uni(v) v.resize(unique(ALL(v))-v.begin())
#define longer __int128_t
void die(string S){puts(S.c_str());exit(0);}
#define x1 x114514
#define y1 y1919810
const ld pi=acos(-1.0);
inline ld sqr(ld x){return x*x;}
int N,n;
ld x[1005],y[1005];
ld dist[1005];
ld cx,cy;
int p;
ld getLoss(int m,ld diff)
{
	ld Angle=atan2(y[p]-cy,x[p]-cx);
	ld rot=pi*2/m;
	ld ang=pi*(m-2)/m;
	ld Loss=0;
	for(int i=1;i<=N;i++)
	{
		ld A=Angle+diff,B=rot+Angle+diff;
		ld angle=atan2(y[i]-cy,x[i]-cx);
		ld d=angle-Angle-diff;
		while(d<0)
		{
			d+=rot;
			A-=rot;
			B-=rot;
		}
		while(d>rot)
		{
			d-=rot;
			A+=rot;
			B+=rot;
		}
		ld val=sin(ang/2)/sin(pi-ang/2-d);
		ld x1=cos(A)+cx,y1=sin(A)+cy;
		ld x2=cos(B)+cx,y2=sin(B)+cy;
		ld AA=y2-y1,BB=x1-x2,C=-(AA*x1+BB*y1);
		ld D=(x[i]*AA+y[i]*BB+C)/sqrtl(sqr(AA)+sqr(BB));
		Loss+=sqr(D/val);
	}
	return Loss;
}
ld getLoss(int m)
{
	ld Result=1e18;
	const int B=3;
	const ld Margin=asin(0.04);
	for(ld diff=-Margin;diff<=Margin;diff+=Margin/B)
		Result=min(Result,getLoss(m,diff));
	return Result;
}
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int t;
	cin>>t;
	while(t--)
	{
		cin>>N>>n;
		for(int i=1;i<=N;i++)
			cin>>x[i]>>y[i];
		cx=cy=0.0;
		for(int i=1;i<=N;i++)
		{
			cx+=x[i];
			cy+=y[i];
		}
		cx/=N;
		cy/=N;
		for(int i=1;i<=N;i++)
			dist[i]=sqrtl(sqr(x[i]-cx)+sqr(y[i]-cy));
		p=max_element(dist+1,dist+N+1)-dist;
		ld Loss=1e18;
		int Answer=-1;
		for(int i=max(3,n-5);i<=n;i++)
		{
			ld loss=getLoss(i);
			if(loss<Loss)
			{
				Loss=loss;
				Answer=i;
			}
		}
		cout<<Answer<<'\n';
	}
	return 0;
}