#include <bits/stdc++.h>
#define FOR(i,m,n) for(int i=m;i<n;++i)
#define RFOR(i,m,n) for(int i=m;i>=n;--i)
#define in(val) cin>>val
#define out(val) cout<<val
#define lli long long int
#define MOD 1000000007
#include <iostream>
using namespace std;

struct cor{
    int x,y;
};


class solution{
    int test,x1,y1,x2,y2,n;
public:
    solution();

};

bool cmp(cor A,cor B){
    if(A.x==B.x)
        return A.y<B.y;
    return A.x<B.x;
}

solution::solution(){
    in(test);
    while(test--){
        in(n);
        x1=INT_MAX,x2=INT_MIN,y1=INT_MAX,y2=INT_MIN;
        int flag=0;
        struct cor arr[n];
        FOR(i,0,n){
            in(arr[i].x);in(arr[i].y);
        }
        if(n==1||n==2){
            out("YES\n");
            continue;
        }
        if(n==3){
            sort(arr,arr+n,cmp);
            if((arr[0].x!=arr[1].x)&&(arr[1].x!=arr[2].x)){
                if((arr[0].y<arr[1].y&&arr[1].y<arr[2].y)||(arr[0].y>arr[1].y&&arr[1].y>arr[2].y)){
                    out("NO\n");
                    continue;
                }
            }
            out("YES\n");
            continue;
        }
        FOR(i,0,n){
            if(arr[i].x<x1)
                x1=arr[i].x;
            if(arr[i].y<y1)
                y1=arr[i].y;
            if(arr[i].x>x2)
                x2=arr[i].x;
            if(arr[i].y>y2)
                y2=arr[i].y;
        }
        FOR(i,0,n){
            if(arr[i].x!=x1&&arr[i].x!=x2&&arr[i].y!=y1&&arr[i].y!=y2){
                flag=1;
                out("NO\n");
                break;
            }
        }
        if(!flag)
            out("YES\n");
    }
}

int main(){
    solution obj;
}