q = int(input())
for i in range(q):
    n = int(input())
    if n <= 2:
        print("YES")
        continue
    a = [[]] * n
    for j in range(n):
        a[j] = [int(l) for l in input().split()]
    ans = False
    for i in range(n):
        if ans:
            break
        for j in range(n):
            if ans:
                break
            for k in range(n):
                if i != j and j != k and i != k:
                    if (a[j][0] == a[i][0] and a[k][1] == a[j][1]):
                        check = True;
                        for l in range(n):
                            if (a[l][0] == a[j][0] and
                                            min(a[i][1], a[j][1]) <= a[l][1] <= max(a[i][1], a[j][1])) or \
                                    (a[l][1] == a[j][1] and min(a[k][0], a[j][0]) <= a[l][0] <= max(a[k][0], a[j][0])):
                                check = True
                            else:
                                check = False
                                break
                        if(check):
                            print("YES")
                            ans = True
                            break
    if ans:
        continue
    print("NO")