#include <cmath>
#include <cstdio>
#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;
        vector<pair<int,int> > arr(n);
        vector<int> arr_x(n),arr_y(n);
        bool flag = true;
        for(int i=0 ; i<n ; i++){
            cin >> arr[i].first >> arr[i].second;
            arr_x[+i] = arr[i].first;
            arr_y[i] = arr[i].second;
        }
        int max_x = *max_element(arr_x.begin(),arr_x.end());
        int max_y = *max_element(arr_y.begin(),arr_y.end());
        int min_x = *min_element(arr_x.begin(),arr_x.end());
        int min_y = *min_element(arr_y.begin(),arr_y.end());

        if((max_x > 0 && min_x < 0) || (max_y > 0 && min_y < 0)){
            cout << "NO\n";
            continue;
        }
          
        for(int i=0 ; i<n ; i++){
                if((arr[i].first == max_x || arr[i].first == min_x) && (arr[i].second > max_y || arr[i].second < min_y) ){
                    flag = false;
                    break;
                }
                if(arr[i].first < max_x && arr[i].first > min_x && arr[i].second!=min_y && arr[i].second != max_y){
                    flag = false;
                    break;
                }
        }
        if(flag) cout << "YES\n";
        else cout << "NO\n";
    }
    
    return 0;
}