#include <bits/stdc++.h>

using namespace std;

int main()
{
    int p, qi, q,n, x, y, c, d;
    scanf("%d", &qi);
    while(qi--)
    {
        scanf("%d", &n);

        int f = 1, d = 0, c = 0;
        while(n--)
        {
            scanf("%d %d", &p, &q);
            if( c==0 && p==0 && q!=0) x = q, c = 1;
            if( d==0 && p!=0 && q==0) y = q, d = 1;
            if(p==0 && q==0) continue;
            if(d==1&&c==1)
            {
                if((q==0&&p<=x) || (p==0&&q<=y)||(p==x&&q<=y)||(q==y&&p<=x)||(q==0&&p>=x) || (p==0&&q>=y)||(p==x&&q>=y)||(q==y&&p>=x)) continue;
                else
                {
                    f = 0;
                }
            }
        }
        if(f==1) printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}