# Enter your code here. Read input from STDIN. Print output to STDOUT
for i in xrange(int(raw_input())):
    n=int(raw_input())
    if n<=3:
        x,y=[],[]
        for j in xrange(n):
            s=map(int,raw_input().split())
            x.append(s[0])
            y.append(s[1])
        print "YES"
    else:
        f,x,y=0,[],[]
        for j in xrange(n):
            s=map(int,raw_input().split())
            x.append(s[0])
            y.append(s[1])
        for j in xrange(n):
            if ((max(x)-min(x))*(y[j]-min(y))==0 or (max(x)-min(x))*(y[j]-max(y))==0 or (max(y)-min(y))*(x[j]-max(x))==0 or (max(y)-min(y))*(x[j]-min(x))==0) and (x[j]!=max(x) and x[j]!=min(x)) and (y[j]!=max(y) and y[j]!=min(y)):
                f=1
                break
        if f==0:
            print "NO"
        else:
            print "YES"