#include<bits/stdc++.h>

using namespace std;
unsigned long long ct = 0;

bool compare(pair<int,int> p1,pair<int,int> p2)
{
    if(p1.first < p2.first)
        return true;
    else
        return false;
}
bool compare1(pair<int,int>p1 ,pair<int,int> p2)
{
    if(p1.second < p2.second)
        return true;
    else
        return false;
}
int main()
{
    int q;
    cin>>q;

    while(q--)
    {
        int n;
        cin>>n;
        vector<pair<int,int> > vec;
        for(int i=0; i<n; i++)
        {
            int x,y;
            cin>>x>>y;
            pair<int,int> p(x,y);
            vec.push_back(p);
        }
        sort(vec.begin(),vec.end(),compare1);
        int y = vec[0].second;
        int y1 = vec[n-1].second;

        sort(vec.begin(),vec.end(),compare);
        int x  = vec[0].first;
        int x1 = vec[n-1].first;

        int i;
        for(i=0; i<vec.size(); i++)
        {
            int m = vec[i].first;
            int n = vec[i].second;
            if(m > x && m < x1 && n > y && n < y1)
                break;
        }
        if(i == vec.size())
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }
}