#include<bits/stdc++.h>
using namespace std;
constexpr int N=200005;
const long double PI=acosl(-1);
constexpr long double eps=1e-15;
class Point
{
public:
    int x,y;
    Point(){x=0,y=0;}
    Point(const int &_x,const int &_y):x(_x),y(_y) {}
    friend Point operator + (const Point &a,const Point &b)
    {
        return Point(a.x+b.x,a.y+b.y);
    }
    friend Point operator - (const Point &a,const Point &b)
    {
        return Point(a.x-b.x,a.y-b.y);
    }
    friend long long cross(const Point &a,const Point &b)
    {
        return (long long)a.x*b.y-(long long)a.y*b.x;
    }
    friend long long dot(const Point &a,const Point &b)
    {
        return (long long)a.x*b.x+(long long)a.y*b.y;
    }
    long double angle()const
    {
        return atan2l(y,x);
    }
    int quadrant()const
    {
        if(x>0&&y>=0) return 1;
        else if(x<=0&&y>0) return 2;
        else if(x<0&&y<=0) return 3;
        else if(x>=0&&y<0) return 4;
        else return 0;
    }
    long double length()const
    {
        return sqrtl((long long)x*x+(long long)y*y);
    }
};
bool cmp_polar_angle(const Point &a,const Point &b)
{
    int x=a.quadrant(),y=b.quadrant();
    if(x!=y) return x<y;
    return cross(a,b)>0;
}
int n,k;
Point p[N];
long double d[N];
void solve()
{
    cin>>n>>k;
    for(int i=0;i<n;i++)
        cin>>p[i].x>>p[i].y;
    sort(p,p+n,cmp_polar_angle);
    if(k==n)
    {
        long double ans=PI*2;
        cout<<fixed<<setprecision(10)<<ans<<"\n";
        return;
    }
    for(int i=0;i<n;i++)
    {
        d[i]=p[i].angle();
        if(d[i]<-eps) d[i]+=PI*2;
    }
    long double ans=0;
    for(int i=0;i<n;i++)
    {
        int j=(i+k)%n;
        long double cur=d[j]-d[i];
        if(cross(p[i],p[j])<0) cur+=PI*2;
        ans=max(ans,cur);
    }
    cout<<fixed<<setprecision(10)<<ans<<"\n";
    return;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr),cout.tie(nullptr);
    int T;
    cin>>T;
    while(T--)
        solve();
    return 0;
}