#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
#define all(a) a.begin(), a.end()
#define rep(i, a, b) for(ll i = a; i < b; i++)

const ld PI = acosl(-1);
const ld PI2 = PI * 2;

ld mod_PI2(ld x){
    while(x < 0) x += PI2;
    while(x >= PI2) x -= PI2;
    return x;
}

void solve(){
    int n,k;
    cin >> n >> k;
    vector<ld> angle(n);
    rep(i,0,n){
        ld x,y;
        cin >> x >> y;
        angle[i] = atan2l(y, x);
    }
    sort(all(angle));

    ld ans = 0;
    rep(i,0,n){
        ans = max(ans, mod_PI2(angle[(i+k)%n] - angle[i]));
    }
    if(ans == 0) ans = PI2;

    cout << fixed << setprecision(20);
    cout << ans << endl;
}

int main(){
    int t;
    cin >> t;
    while(t--){
        solve();
    }
}