# Enter your code here. Read input from STDIN. Print output to STDOUT
def check(arr):
    d = sorted(arr)
    first = []
    last = []
    two = []
    x = d[0][0]
    #first.append(x)
    y = d[len(d)-1][0]
    #last.append(y)
    for i in range(len(d)):
        if d[i][0]==x:
            first.append(d[i][1])
        elif d[i][0]==y:
            last.append(d[i][1])
        else:
            #print 'lo'
            if len(two)<2:
                if d[i][1] not in two:
                    two.append(d[i][1])
            if len(two)==2:
                if d[i][1] not in two:
                    return 'NO'
    #print two
    #print last
    #print first
    if len(two)<1:
        return 'YES'
    
    elif(len(two))==1:
        for i in range(len(first)-1):
            if( (two[0]-first[i])*(two[0]-first[i+1])<0):
                return 'NO'
        for i in range(len(last)-1):
            if( (two[0]-last[i])*(two[0]-last[i+1])<0):
                return 'NO'
        for i in range(len(last)):
            for j in range(len(first)):
                if(two[0]-last[i])*(two[0]-first[j])<0:
                    return 'NO'
    else:        
        for i in first:
            if i>max(two):
                return 'NO'
            if i<min(two):
                return 'NO'
        for i in last:
            if i>max(two):
                return 'NO'
            if i<min(two):
                return 'NO'
    
    return 'YES'

t = int(input())
while t>0:
    q = int(input())
    arr = []
    while q>0:
        x,y = [int(x) for x in raw_input().split()]
        arr.append([x,y])
        q-=1
    print check(arr)
    t-=1