#include <bits/stdc++.h>
#define endl '\n'

using namespace std;


int tests,current_case;


void message(int current_case) {
    //cerr<<"Case "<<current_case<<" solved!"<<endl;
    fprintf(stderr, "Case %d solved!\n", current_case);
}



int main() {
    //ios_base::sync_with_stdio(false);
    //cin.tie(NULL);
    int i,x,y;
    int rows,cols;
    int n;
    map < int, bool > mr, mc;

    //tests=1;
    scanf("%d", &tests);
    for(current_case=1;current_case<=tests;current_case++) {
        scanf("%d", &n);
        rows=0;
        cols=0;
        mr.clear();
        mc.clear();
        for(i=1;i<=n;i++) {
            scanf("%d %d", &x, &y);
            if(mr.find(x)==mr.end()) mr[x]=true,++rows;
            if(mc.find(y)==mc.end()) mc[y]=true,++cols;
        }
        if(rows<=2 && cols<=2) printf("YES\n");
        else printf("NO\n");
        message(current_case);
    }

    return 0;
}