#include<bits/stdc++.h>
using namespace std;
namespace staring
{
    typedef long long LL;
    typedef vector<int> VEC;
    typedef pair<int,int> PII;
    typedef pair<LL,LL> PLL;
    #define fir first
    #define sec second

    #define FOR(i,a,b) for(int i=(a),__i=(b);i<=__i;i++)
    #define ROF(i,a,b) for(int i=(a),__i=(b);i>=__i;i--)

    template<typename TYPE>
    TYPE gmax(TYPE &x,const TYPE y){return x<y?x=y:x;}
    template<typename TYPE>
    TYPE gmin(TYPE &x,const TYPE y){return y<x?x=y:x;}

    static constexpr int SIZE=1<<20;
    static char buffin[SIZE]{},*pin1{},*pin2{};
    static char buffout[SIZE]{},*pout{buffout};
    #define GETC() (pin1==pin2&&(pin2=(pin1=buffin)+fread(buffin,1,SIZE,stdin),pin1==pin2)?EOF:*pin1++)
    #define PUTC(c) (pout-buffout==SIZE&&(fwrite(buffout,1,SIZE,stdout),pout=buffout),*pout++=c)
    template<typename TYPE>
    void read(TYPE &x)
    {
        static int signf{0},chin{0};
        x=signf=0,chin=GETC();
        while(chin<'0'||chin>'9')signf|=chin=='-',chin=GETC();
        while(chin>='0'&&chin<='9')x=(x<<3)+(x<<1)+(chin^48),chin=GETC();
        if(signf)x=-x;
    }
    template<typename TYPE>
    void write(TYPE x,char ch=' ')
    {
        static char stack[64]{},top{0};
        !x&&PUTC('0'),x<0&&(x=-x,PUTC('-'));
        while(x)stack[top++]=x%10|48,x/=10;
        while(top)PUTC(stack[--top]);
        if(ch)PUTC(ch);
    }

}using namespace staring;

constexpr int N=2e5+5,M=N<<1;
constexpr double EPS=1e-8,PI=acos(-1);
typedef complex<double> point;

int n;
point p[M];
mt19937 seed(time(0));
uniform_real_distribution<double> rnd(0,EPS);
pair<double,int> x[M],y[M];
int signx[M],signy[M];
int success;

int f(double theta)
{
    if(success)return 0;
    point rotate={cos(theta),sin(theta)};
    FOR(i,1,n<<1)
    {
        point t=p[i]*rotate;
        x[i]={t.real(),i},y[i]={t.imag(),i};
    }

    nth_element(x+1,x+n,x+(n<<1|1));
    nth_element(y+1,y+n,y+(n<<1|1));
    FOR(i,1,n<<1)signx[x[i].sec]=i>n,signy[y[i].sec]=i>n;

    // FOR(i,1,n<<1)
    //     cerr<<theta<<' '<<i<<' '<<signx[i]<<' '<<signy[i]<<endl;

    int cnt=0;
    FOR(i,1,n)cnt+=signx[i]&&signy[i];
    //     signx[i]&&signy[i]&&(cout<<i<<' ');
    // cout<<endl;
    // cerr<<theta<<' '<<cnt<<' ';
    FOR(i,n+1,n<<1)cnt-=!signx[i]&&!signy[i];
    //     !signx[i]&&!signy[i]&&(cout<<i<<' ');
    // cout<<"--------------\n";
    // cerr<<cnt<<endl;

    if(!cnt)
    {
        success=1;
        int x1=max_element(x+1,x+n+1)->fir,x2=min_element(x+n+1,x+(n<<1|1))->fir;
        int y1=max_element(y+1,y+n+1)->fir,y2=min_element(y+n+1,y+(n<<1|1))->fir;
        point white={(x1+x2)/2,(y1+y2)/2};white=white/rotate;
        printf("%lf %lf\n",white.real(),white.imag());
        // cerr<<theta<<' '<<x1<<' '<<x2<<' '<<y1<<' '<<y2<<endl;
        // FOR(i,1,n<<1)
        //     cerr<<i<<' '<<signx[i]<<' '<<signy[i]<<endl;

        VEC blue[2][2];
        FOR(i,n+1,n<<1)blue[signx[i]][signy[i]].push_back(i);
        FOR(i,1,n)
        {
            printf("%d ",blue[!signx[i]][!signy[i]].back()-n);
            blue[!signx[i]][!signy[i]].pop_back();
        }
        puts("");
    }

    return cnt;
}

void solve()
{
    read(n);
    FOR(i,1,n<<1)
    {
        int a,b;read(a),read(b);
        p[i]={a+rnd(seed),b+rnd(seed)};
    }

    success=0;
    double l=0,r=PI/2;
    int fl=f(l),fr=f(r);
    // cerr<<fl<<' '<<fr<<endl;
    while(!success)
    {
        double mid=(l+r)/2;
        int fmid=f(mid);
        if(1ll*fmid*fl<0)r=mid,fr=fmid;
        else l=mid,fl=fmid;
    }
}

int main()
{
    int T;read(T);
    while(T--)solve();

    fwrite(buffout,1,pout-buffout,stdout);
    return 0;
}