#include<iostream>
#include<vector>
#include<stdio.h>
#include<math.h>
#include<algorithm>
#include<map>
#include<utility>
#include<string>
#include<sstream>
#include<set>
#include<stack>
#include<queue>
using namespace std;
#define f(i,a,b) for(ll i=a;i<b;i++)
#define fr(i,a,b) for(ll i=a;i>=b;i--)
#define ff(i,a,b,c) for(int i=a;i<b;i+=c)
#define w(n) while(n>0)
#define vi vector<int>
#define vll vector<long long int>
typedef pair<int,int> P;
typedef pair<pair<int,int> ,int> PII;
typedef pair<pair<long long int,long long int> ,long long int> PLL;
typedef pair<long long int,long long int> PL;
typedef long long ll;
typedef long double ld;
typedef int I;
typedef string S;
ll gcd(ll n,ll m){if(m<=n && n%m==0)return m;if(n<m)return gcd(m,n);else return gcd(m,n%m);}
ll add(ll a,ll b,ll md){a=((a%md)+(b%md))%md;return a;}
ll sub(ll a,ll b,ll md){return add(a,md-b,md);}
ll bC(int n,int r){ll ans=1;if(r>n-r)r=n-r;f(i,1,r+1)ans=(ans*(n-i+1))/(i);return ans;}
ll mul(ll a,ll b,ll mod){a%=mod;b%=mod;ld res=a;res*=b;ll c=(ll)(res/mod);a*=b;a-=c*mod;a%=mod;if(a<0)a+=mod;return a;}
ll mod_pow(ll a,ll b,ll mod){ll ans=1;while(b){if(b&1)ans=mul(ans,a,mod);a=mul(a,a,mod);b>>=1;}return ans;}
ll div(ll x,ll y,ll mod){return mul(x,mod_pow(y,mod-2,mod),mod);}
int main(){
    ll q , n , x , y ;
    map< ll , I > mp1 , mp2;
    cin >> q;
    w( q ) {
        q-- ; 
        cin >> n ;
        f(i, 0, n ) {
            cin >> x >> y ;
            mp1[ x ] = 1;
            mp2[ y ] = 1;
        }
        if( mp1.size()  > 2 || mp2.size() > 2 ) cout << "NO" << endl;
        else cout << "YES" << endl;
        mp1.clear();
        mp2.clear();
    }
}