#include<stdio.h>

int min(int a,int b);
int max(int a,int b);

int main()
{
    int x1,y1,x2,y2;
    int q,n;
    int x,y;
    int point[10][2];
    int i,j,k;

    scanf("%d",&q);
    while(q--)
    {
        scanf("%d",&n);
        for(i=0;i<n;i++)
            scanf("%d %d",&point[i][0],&point[i][1]);

        if(n<=2)
            printf("YES\n");
        else
        {
            x1=min(point[0][0],point[0][1]);
            y1=max(point[0][1],point[1][1]);
            x2=max(point[0][1],point[0][1]);
            y2=min(point[0][1],point[1][1]);

            for(i=2;i<n;i++)
            {
                x=point[i][0];
                y=point[i][1];

                if(x1==x2 || y1==y2)
                {
                    x1=min(x1,x);
                    y1=max(y1,y);
                    x2=max(x2,x);
                    y2=min(y2,y);
                    continue;
                }

                if(point[i][0]<x1 || point[i][0]>x2 || point[i][1]>y1 || point[i][1]<y2)
                    break;

                if(x>x1 && x<x2)
                    break;
                if(y<y1 && y>y2)
                    break;

                x1=min(x1,x);
                y1=max(y1,y);
                x2=max(x2,x);
                y2=min(y2,y);
            }
            if(i==n)
                printf("YES\n");
            else
                printf("NO\n");
        }
    }
}

int min(int a,int b)
{
    return (a<b)?a:b;
}

int max(int a,int b)
{
    return (a>b)?a:b;
}