#include <bits/stdc++.h>

using namespace std;
int cntV[20005], cntH[20005];
vector<pair<int,int> > vec;

bool exista(int a, int b)
{
    pair<int,int> x(a,b);
    return find(vec.begin(), vec.end(), x) != vec.end();
}

int main()
{
   /// freopen("B.in","r",stdin);
    int T,N;
    cin >> T;
    while(T--)
    {
        cin >> N;
        int a,b;
        memset(cntV,0,sizeof(cntV));
        memset(cntH,0,sizeof(cntH));
        vec.clear();

        for(int i = 1; i <= N; ++i){
            cin >> a >> b;
            a += 10000;
            b += 10000;
            vec.push_back({a,b});
            cntV[a]++;
            cntH[b]++;
        }
        int lat1 = -1,lat2 = -1,lat3 = -1,lat4 = -1;
        for(int i = 0; i <= 20000; ++i)
        {
            if(cntV[i] && lat1 == -1)
                lat1 = i;
            if(cntH[i] && lat2 == -1)
                lat2 = i;
        }

        for(int i = 20000; i >= 0; --i)
        {
            if(cntV[i] && lat3 == -1 && i > lat1)
                lat3 = i;
            if(cntH[i] && lat4 == -1 && i > lat2)
                lat4 = i;
        }
        int crt = 0;
        int total = 0;
        if(lat1 != -1){
            ++crt;
            total += cntV[lat1];
        }
        if(lat2 != -1) {
            total += cntH[lat2];
        }
        if(lat3 != -1) {
            total += cntV[lat3];
        }
        if(lat4 != -1) {
            total += cntH[lat4];
        }

        if(exista(lat1, lat2))
            --total;
        if(exista(lat1, lat4))
            -- total;
        if(exista(lat3,lat2))
            --total;
        if(exista(lat3,lat4))
            --total;
        if(total == N)
            cout << "YES\n";
        else
            cout << "NO\n";

    }
    return 0;
}