#include <cmath>
#include <climits>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int q;
    cin>>q;
    while(q--)
    {
        int n;
        cin>>n;
        int x=INT_MIN,y=INT_MIN;
        bool f=1,neg=0;
        int a[n],b[n];
        int i,j;
        for(i=0;i<n;i++)
        {
            cin>>a[i]>>b[i];
            if(a[i]<0 || b[i]<0)
                neg=1;
            y=max(y,abs(b[i]));
            x=max(x,abs(a[i]));
        }
        //cout<<x<<y<<endl;
        if(f==0)
                cout<<"NO";
        else{
            for(i=0;i<n;i++)
            {
                if(neg==0 && ((a[i]==0 && b[i]<y)))
                        f=1;
                else if(abs(a[i])>x && abs(b[i])==0  || abs(b[i])>y && abs(a[i])==0)
                    {
                        f=0;
                        break;
                        }
                else if(abs(a[i])<x && abs(b[i])<y)
                {
                    f=0;
                    break;
                }
            }
            if(f==1)
                cout<<"YES";
            else cout<<"NO";
        }
        cout<<endl;
    }
    return 0;
}