#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define MAX (int)1e6+50
#define PI acos(-1.0)

struct point {
    ll x, y;
}p[MAX];

// 计算向量的点积
ll pmul(point p1, point p2) {
    return p1.x * p2.x + p1.y * p2.y;
}

// 计算向量的模长
double dis(point p) {
    return sqrt(p.x * p.x + p.y * p.y);
}

// 计算两向量的叉积
ll xmul(point p1, point p2) {
    return p1.x * p2.y - p1.y * p2.x;
}

int xx(point a) //判断象限
{
    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;
}

bool cmp(point a, point b)   //先按象限从小到大排序 再按极角从小到大排序
{
    if (xx(a) == xx(b)) return xmul(a, b) > 0;   //逆时针排序
    else return xx(a) < xx(b);
}

// 计算两向量间的夹角（以弧度表示，范围为 [0, 2 * pi]）
double angle_vec(point p1, point p2) {
    double res = atan2(p2.y, p2.x) - atan2(p1.y, p1.x);
    if (res < 0)
        res += 2 * PI;
    return res;
}

int main()
{
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
    int T;
    cin >> T;
    while (T--) {
        int n, k, i, j;
        cin >> n >> k;
        for (i = 0; i < n; i++) {
            cin >> p[i].x >> p[i].y;
            //p[i + n] = p[i];
        }
        double res = 0;
        if (n == k) {
            res = 2 * PI;
            cout << fixed << setprecision(10) << res << '\n';
            continue;
        }
        sort(p, p + n, cmp);
        //for (i = 0; i < n; i++) {
        //    cout << p[i].x << ' ' << p[i].y << '\n';
        //}
        for (i = 0; i < n; i++) {
            p[i + n] = p[i];
        }
        for (i = 0; i < n; i++) {
            res = max(res, angle_vec(p[i], p[i + k]));
        }
        cout << fixed << setprecision(10) << res << '\n';
    }
}