#include<bits/stdc++.h>
using namespace std;
//#define int long long
#define debug(x) cout<<x<<"--------------------------------------\n" ;
const int N = 1e5 + 10;
typedef long long ll;
const int INF = 1e9 ;
const int MOD = 1e9 + 7 ;
typedef pair<int,int> PII ;
int gcd(int a,int b){
    return b ? gcd(b,a%b) : a ;
}
ll qpow(int a,int k){
    ll res = 1 ;
    while (k){
        if(k&1) res = 1ll * res * a % MOD ;
        a = 1ll * a * a % MOD ;
        k >>= 1 ;
    }
    return res ;
}
int n;
int k;
const double PI = acos(-1.0);

#define double long long
const double eps = 0;
inline int sgn(double x){
    return fabs(x)<=eps?0:(x<0?-1:1);
}
struct point {
    double x, y;
    int id;
    point(double a = 0, double b = 0, int c = 0): x(a), y(b), id(c) {
    }
    point operator +(const point &A) const {
        return point(x + A.x, y + A.y);
    }
    point operator -(const point &A) const {
        return point(x - A.x, y - A.y);
    }
    point operator *(const double v) const {
        return point(x * v, y * v);
    }
    point operator /(const double v) const {
        return point(x / v, y / v);
    }
    bool operator ==(const point &A) const {
        return sgn(x - A.x) == 0 && sgn(y - A.y) == 0;
    }
    double norm() const {
        return sqrt(x * x + y * y);
    }
    bool operator<(const point &a) const {
        if (abs(x - a.x) <= eps) return y < a.y - eps;
        return x < a.x - eps;
    }
    bool operator>(const point &a) const { return !(*this < a || *this == a); }
    double operator^(const point &a) const { return x * a.y - y * a.x; } // 叉积，注意优先级
    double operator*(const point &a) const { return x * a.x + y * a.y; }
    int toleft(const point &a) const {
        const auto t = (*this) ^ a;
        return (t > eps) - (t < -eps);
    } // to-left 测试
    point rot(const double cosr, const double sinr) const { return {x * cosr - y * sinr, x * sinr + y * cosr}; }
    // 逆时针旋转（给定角度的正弦与余弦）
};
bool cmp(point a,point b){
    auto quad=[](const point &a){
        if (a.y<-eps) return 1;
        if (a.y>eps) return 4;
        if (a.x<-eps) return 5;
        if (a.x>eps) return 3;
        return 2;
    };
    int qa = quad(a) , qb = quad(b); // 找象限
    if(qa != qb) return qa < qb;
    auto t = (a^b);
    if(abs(t)<=eps) return (a*a) < (b*b) - eps;
    return t > eps;
}
using Points = vector<point>;
#undef double
void solve(){
    cin >> n >> k;
    Points p(n);
    for(int i=0;i<n;i++){
        cin >> p[i].x >> p[i].y;
    }
    cout << fixed << setprecision(10);
    if(n==k){
        cout << 2.0 * PI << '\n';
        return;
    }
    std::sort(p.begin(), p.end(),cmp);
    double ans = 0;
    for(int i=0;i<n;i++){
        int j = (i+k) % n;
        double t1 = atan2(p[i].y,p[i].x);
        double t2 = atan2(p[j].y,p[j].x);
        if(t2<t1){
            if(t2-t1<0){
                ans = max(ans,t2-t1+2*PI);
            }
        }
        ans = max(ans,t2-t1);
    }
    cout << ans << '\n';
}
signed main(){
    ios::sync_with_stdio(false) ;
    cin.tie(0) ;
    int tt = 1 ;
    cin >> tt ;
    while (tt--) solve() ;
    return 0 ;
}