#include <bits/stdc++.h>
using namespace std;

int main() {
    int q;
    cin>>q;
    while(q--){
        int n,mnlt=INT_MAX,mnrt=INT_MAX,mxlt=INT_MIN,mxrt=INT_MIN;
        cin>>n;
        vector<int> left(n),right(n);
        for(int i=0;i<n;i++){
            cin>>left[i]>>right[i];
            //cout<<left[i]<<" "<<right[i]<<" ";
            if(left[i]<mnlt) mnlt=left[i];
            if(right[i]<mnrt) mnrt=right[i];
            if(left[i]>mxlt) mxlt=left[i];
            if(right[i]>mxrt) mxrt=right[i];
        }
        //cout<<mn<<" "<<mx<<" ";
        bool f=0;
        for(int i=0;i<n;i++){
            int x=left[i],y=right[i];
            if(x!=mnlt&&x!=mxlt&&y!=mnrt&&y!=mxrt){
                cout<<"NO"<<endl;
                f=1;
                break;
            }
        }
        if(f==0) cout<<"YES"<<endl;
    }
    return 0;
}