#include <bits/stdc++.h>

using namespace std;

#define pb push_back
#define mp make_pair
#define ll long long int
#define s(x) scanf("%d", &x)
#define sd(x) scanf("%lf", &x)
#define sl(x) scanf("%lld", &x)
#define mod 1000000007
#define get getchar_unlocked
#define INF 1000000000000000000LL

bool check(int x, int y, int z)
{
    return (min(x,y) <= z && z <= max(x,y));
}

int main()
{
    int t, i, j, k, l, m, n, p, q;
    vector <int> x, y;
    vector < pair <int, int> > v;
    s(t);
    while (t--) {
        s(n);
        x.clear();
        y.clear();
        v.clear();
        for (i = 0; i < n; ++i) {
            s(p);
            s(q);
            v.pb(mp(p,q));
            x.pb(p);
            y.pb(q);
        }
        for (i = 0; i < x.size(); ++i) {
            for (j = i; j < x.size(); ++j) {
                for (k = 0; k < y.size(); ++k) {
                    for (l = k; l < y.size(); ++l) {
                        for (m = 0; m < n; ++m) {
                            if (v[m].first == x[i] && check(y[k], y[l], v[m].second))
                                continue;
                            if (v[m].first == x[j] && check(y[k], y[l], v[m].second))
                                continue;
                            if (v[m].second == y[k] && check(x[i], x[j], v[m].first))
                                continue;
                            if (v[m].second == y[l] && check(x[i], x[j], v[m].first))
                                continue;
                            goto l1;
                        }
                        printf("YES\n");
                        goto l2;
                        l1: ;
                    }
                }
            }
        }
        printf("NO\n");
        l2: ;
    }
    return 0;
}