#include <bits/stdc++.h>
#define ll long long
#define endl '\n'
#define pi 3.14159265358979
using namespace std;

const int N=4e5+10;
double deg[N];
int n,k;
void solve()
{
    cin>>n>>k;
    for(int i=1;i<=n;i++)
    {
        int x,y;
        cin>>x>>y;
        deg[i]=atan2(y,x);
    }
    sort(deg+1,deg+n+1);
    for(int i=1;i<=n;i++)
        deg[i+n]=deg[i]+2*pi;
    int l=1,r=k+1;
    double ans=0,tmp,lastans=0;
    while(l<=n)
    {
        tmp=deg[r]-deg[l];
        ans=max(ans,tmp);
        l++;
        r++;
    }
    cout<<fixed<<setprecision(8);
    cout<<ans<<endl;
    return ;
}
signed main()
{
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    int o=1;
    cin>>o;
    while(o--) solve();
    return 0;
}