#include<bits/stdc++.h>
#define pi pair<int,int>
#define pb push_back
#define vec vector<int>
using namespace std;
#define int long long
#define M 998244353
void in(int &x){
    int f=1;x=0;
    char c=getchar();
    while(!isdigit(c)&&c!='-')c=getchar();
    if(c=='-')f=-1,c=getchar();
    while(isdigit(c))x=x*10+c-'0',c=getchar();
    x*=f;
}
int t,n,m,k,x,y;
double a[2000005];
void solve(){
    in(n);in(m);
    for(int i=1;i<=n;i++){
        in(x);in(y);
        a[i]=atan2(y,x);
    }
    sort(a+1,a+1+n);for(int i=1;i<=n;i++)a[i+n]=a[i];
    double ans=0,p=2*acos(-1.0);
    if(m==n){
        printf("%.9lf\n",p);
        return;
    }
    for(int i=1;i<=n;i++){
        if(a[i+m]>=a[i])ans=max(ans,a[i+m]-a[i]);
        else ans=max(ans,a[i+m]-a[i]+p);
    }
    printf("%.9lf\n",ans);
}
signed main(){
    in(t);
    while(t--)solve();
}