# Enter your code here. Read input from STDIN. Print output to STDOUT
q = input()
for _ in range(q):
    n = input()
    
    x = [0 for i in range(n)]
    y = [0 for i in range(n)]
    for i in range(n):
        x[i], y[i] = map(int, raw_input().split())
        
    xmin = min(x)
    xmax = max(x)
    ymin = min(y)
    ymax = max(y)
    
    #if xmin == xmax or ymin == ymax:
    #    print("NO")
    #    continue
    
    for i in range(n):
        if (x[i] != xmin and x[i] != xmax) and (y[i] != ymin and y[i] != ymax):
            print("NO")
            break
    else:
        print("YES")