#include<bits/stdc++.h>
using namespace std;
#define For(i,a,b) for(int i=(a);i<=(b);i++)
#define Rof(i,a,b) for(int i=(a);i>=(b);i--)
#define db long double
#define ll long long
#define wln putchar('\n')
const int N=200005;
const db eps=1e-10,pi=acos(-1);
struct vec2{int x,y;}p[N*2];
ll operator *(vec2 a,vec2 b){return 1ll*a.x*b.x+1ll*a.y*b.y;}
ll operator /(vec2 a,vec2 b){return 1ll*a.x*b.y-1ll*a.y*b.x;}
db abs(vec2 a){return sqrt((db)(1ll*a.x*a.x+1ll*a.y*a.y));}
int xx(vec2 a)
{
    if(a.x>0&&a.y>=0)return 1;
    if(a.x<=0&&a.y>0)return 2;
    if(a.x<0&&a.y<=0)return 3;
    if(a.x>=0&&a.y<0)return 4;
    return 0;
}
bool cmp(vec2 a,vec2 b)
{
    int xa=xx(a),xb=xx(b);
    if(xa!=xb)return xa<xb;
    return a/b>0;
}
db angle_between(vec2 a,vec2 b)
{
    db t1=atan2(a.y,a.x),t2=atan2(b.y,b.x);
    db t=t2-t1;
    if(t<-eps)t+=2*pi;
    return t;
}
int n,k;
void Main()
{
    scanf("%d%d",&n,&k);
    For(i,1,n)scanf("%d%d",&p[i].x,&p[i].y);
    if(k==n){printf("%.7Lf\n",2*pi); return;}
    sort(p+1,p+n+1,cmp);
    copy(p+1,p+n+1,p+n+1);
    // For(i,1,n)printf("(%d,%d)",p[i].x,p[i].y); wln;
    db ans=0;
    For(i,1,n)
    {
        db t=angle_between(p[i],p[i+k]);
        if(abs(t)<eps&&(i-1)%n>(i+k-1)%n)t+=2*pi;
        ans=max(ans,t);
    }
    printf("%.7Lf\n",ans);
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)Main();
}