#include<bits/stdc++.h>
using namespace std;bool Mbe;
namespace MAOJUN{

typedef long double db;
const int N=2e5+5;
int n,k;db a[N];

const db pi=acos(-1);
inline void slv(){
	scanf("%d%d",&n,&k);
	for(int i=0;i<n;i++){
		db x,y;scanf("%Lf%Lf",&x,&y);a[i]=atan2l(x,y);
	}
	// for(int i=0;i<n;i++)printf("%Lf ",a[i]);puts("");
	if(n==k){printf("%Lf\n",2*pi);return;}
	sort(a,a+n);
	db mx=0;
	for(int i=0;i<n;i++){
		db w=a[(i+k)%n]-a[i];
		if(w<0)mx=max(mx,w+2*pi);
		else mx=max(mx,w);
	}
	printf("%Lf\n",mx);
}
inline void main(){int T;scanf("%d",&T);while(T--)slv();}

}bool Med;int main(){
#ifdef LOCAL
	freopen("1.in","r",stdin);
	freopen("data.out","w",stdout);
	atexit([]{fprintf(stderr,"%.0lfms\n%lfMB\n",clock()*1000./CLOCKS_PER_SEC,(&Mbe-&Med)/1024./1024);});
#endif
	MAOJUN::main();
	return 0;
}