import math
q=int(input())
i=0
while(i<q):
    n=int(input())
    X=[]
    Y=[]
    j=0
    while(j<n):
        x,y=input().strip().split(' ')
        x=int(x)
        y=int(y)
        X.append(x)
        Y.append(y)
        j+=1
    x0=min(X)
    y0=min(Y)
    x3=max(X)
    y3=max(Y)
    #print([x0,y0],[x3,y3])
    k=0
    flag=0
    while(k<len(X)):
        if((X[k]==x0 and (y<=y3 and y>=y0))or
           (X[k]==x3 and (y<=y3 and y>=y0))or
           (Y[k]==y0 and (x<=x3 and x>=x0))or
           (Y[k]==y3 and (x<=x3 and x>=x0))):  
            k+=1
            continue
        else:
            flag=1
            print('NO')
            break
        #k+=1
    if(flag==0):
        print('YES')
    i+=1