#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
#define I inline
#define double long double
using namespace std;

const double PI = 3.14159265358;
const double eps = 1e-8;
const int N = 200100;
struct point {
	int x,y;
}a[N<<1];
char s[N];
int p[N];
int n,m,k;

I double rate(point p1,point p2,int cro) {
	double a1=atan2(p1.y,p1.x),a2=atan2(p2.y,p2.x);
	//cout<<a1<<' '<<a2<<' '<<cro<<endl;
	if(cro) return a2-a1+PI*2;
	return a2-a1;
}
I bool cmp(point p1,point p2) {
	return atan2(p1.y,p1.x)<atan2(p2.y,p2.x);
}
I void solve() {
	cin>>n>>k; 
	for(int i=1;i<=n;++i) cin>>a[i].x>>a[i].y;
	if(n==1) {
		cout<< "6.2831853072"<<endl;
		return ;
	}
	sort(a+1,a+1+n,cmp);
	for(int i=n+1;i<=n*2;++i) a[i]=a[i-n];
	double ans=0;
	for(int i=1;i<=n;++i) {
		point l=a[i],r=a[i+k];
		double rr=rate(l,r,i+k>n);
		ans=max(ans,rr);
		cout<<"!!"<<rr<<endl;
	}
	printf("%.6Lf\n",ans);
	//cout<<ans<<endl;
} 
int main()
{
	int T; cin>>T;
	while(T--) {
		solve();
	}	
}
/*

 5
 1 1
 0 1
 8 2
 1 0
 1 1
 0 1 
 -1 1 
 -1 0 
 -1 -1
 
 0 -1
 1 -1
 4 2
 -1 1
 0 1
 0 2
 1 1
 4 2
 -1000000000 0
 -998244353 1
 
 998244353 1
 1000000000 0
 3 1
 0 1
 0 2
 0 -1
*/