///==================================================///
///                HELLO WORLD !!                    ///
///                  IT'S ME                         ///
///               BISHAL GAUTAM                      ///
///         [ bsal.gautam16@gmail.com ]              ///
///==================================================///
#include<bits/stdc++.h>
#define X first
#define Y second
#define mpp make_pair
#define nl printf("\n")
#define SZ(x) (int)(x.size())
#define pb(x) push_back(x)
#define pii pair<int,int>
#define pll pair<ll,ll>
///---------------------
#define S(a) scanf("%d",&a)
#define P(a) printf("%d",a)
#define SL(a) scanf("%lld",&a)
#define S2(a,b) scanf("%d%d",&a,&b)
#define SL2(a,b) scanf("%lld%lld",&a,&b)
///------------------------------------
#define all(v) v.begin(),v.end()
#define CLR(a) memset(a,0,sizeof(a))
#define SET(a) memset(a,-1,sizeof(a))
#define fr(i,a,n) for(int i=a;i<=n;i++)
using namespace std;
typedef long long ll;

///  Digit     0123456789012345678 ///
#define MX     100005
#define inf    2000000010
#define MD     1000000007
#define eps    1e-9
///===============================///

int n,p[22];
pii pp[22],qq[22];
vector<int>vx,vy;
int main() {
    int tc,x,y,i,j;
    S(tc);
    while(tc--){
        S(n);
        vx.clear();
        vy.clear();
        for(i=0;i<n;i++){
            S2(x,y);
            vx.pb( x );
            vy.pb( y );
            pp[i]=mpp(x,y);
        }
        if(n<=2){
            printf("YES\n");
            continue;
        }
        sort( all(vx) );
        sort( all(vy) );
        vx.resize( unique( all(vx) )-vx.begin() );
        vy.resize( unique( all(vy) )-vy.begin() );
        bool f=0;
        int sx=SZ( vx );
        int sy=SZ( vy );
        if( sx==1 || sy==1 ){
            printf("YES\n");
            continue;
        }
        for(int i=0;i<sx;i++){
            for(int j=i+1;j<sx;j++){
                for(int k=0;k<sy;k++){
                    for(int l=k+1;l<sy;l++){

                        int cnt=0;
                        for(int m=0;m<n;m++){
                            int x=pp[m].X,y=pp[m].Y;
                            if( x==vx[i]&&y<=vy[l]&&y>=vy[k] || x==vx[j]&&y<=vy[l]&&y>=vy[k] || y==vy[k]&&x>=vx[i]&&x<=vx[j] || y==vy[l]&&x>=vx[i]&&x<=vx[j] ){
                                cnt++;
                            }
                            else break;
                        }
                        if( cnt==n ){
                           // cout<<vx[i]<< " : "<<vx[j]<<endl;
                          //  cout<<vy[k]<< " :: "<<vy[l]<<endl;
                            f=1;
                            break;
                        }
                    }
                    if(f)break;
                }
                if(f)break;
            }
            if(f)break;
        }
        if(f)printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}