# Enter your code here. Read input from STDIN. Print output to STDOUT
def onLine(p1,p2,p3):
    if(p1[0]*(p2[1]-p3[1])+p2[0]*(p3[1]-p1[1])+p3[0]*(p1[1]-p2[1]))==0:
        #print p1[0]*(p2[1]-p3[1]) + p2[0]*(p3[1]-p1[0]) + p3[0]*(p1[1]-p2[1])
        return True
    else:
        return False
Q = input()

for _ in xrange(Q):
    n = input()
    listx = []
    listy = []
    for p in xrange(n):
        x,y = map(int,raw_input().split())
        listx.append(x)
        listy.append(y)
    leftbottom = (min(listx),min(listy))
    lefttop = (min(listx),max(listy))
    rightbottom = (max(listx),min(listy))
    righttop = (max(listx),max(listy))
    #print listx,listy
    #print leftbottom,lefttop,rightbottom,righttop
    for i in xrange(n):
        if onLine(leftbottom,lefttop,(listx[i],listy[i])):
            continue
        elif onLine(lefttop,righttop,(listx[i],listy[i])):
            continue
        elif onLine(rightbottom,leftbottom,(listx[i],listy[i])):
            continue
        elif onLine(righttop,rightbottom,(listx[i],listy[i])):
            continue
        else:
            print "NO"
            break
    else:
        print "YES"