T = int(input())
for t in range(T):
    x = {}
    y = {}
    N = int(input())
    p = []
    for n in range(N):
        p.append(list(map(int, input().split())))
        x[p[-1][0]] = x.get(p[-1][0], []) + [n]
        y[p[-1][1]] = y.get(p[-1][1], []) + [n]
    found = (N <= 2)
    sN = sorted(range(N))
    for X1 in x:
        for X2 in x:
            for Y1 in y:
                for Y2 in y:
                    if X1 != X2 or Y1 != Y2:
                        minY1Y2 = min(Y1, Y2)
                        maxY1Y2 = max(Y1, Y2)
                        minX1X2 = min(X1, X2)
                        maxX1X2 = max(X1, X2)

                            
                        good = True
                        for xs, ys in p:
                            if not (((X1!= X2 and xs == X1 or xs == X2) and ys >= minY1Y2 and ys <= maxY1Y2) or ((Y1 != Y2 and ys == Y1 or ys == Y2) and xs >= minX1X2 and xs <= maxX1X2)):
                                good = False
                                break
                        if good:
                            #print(X1, X2, Y1, Y2)
                            found = True
                            
    #print(foundX, foundY)
            
    if found:
        print("YES")
    else:
        print("NO")