# Enter your code here. Read input from STDIN. Print output to STDOUT                 
q=int(raw_input())
for q_0 in range(q):
    n=int(raw_input())
    points=[]
    for n_0 in range(n):
        p=map(int,raw_input().split())
        points.append(p)
    if n==3:
        print 'YES'
    else:
        not_in_tri=points[3:]
        in_tri=points[:3]
        L=[]
        is_true=True
        if is_true==True:
            for i in range(3):
                for j in range(3):
                    if i<j:
                        a=in_tri[i][0]-in_tri[j][0]
                        b=in_tri[i][1]-in_tri[j][1]
                        c=in_tri[i][0]*(in_tri[i][1]-in_tri[j][1])-in_tri[j][1]*(in_tri[i][0]-in_tri[j][0])
                        for i_1 in not_in_tri:
                            if a*(i_1[1])-b*(i_1[0])+c!=0:
                                print 'NO'
                                is_true=False
                                break
                        if is_true==False:
                            break
                if is_true==False:
                            break