q = int(input())


for _ in range(q):
    n = int(input())
    
    done = False
    res = True
    allowed_x = []
    allowed_y = []
    for _ in range(n):        
       
        
        x, y = map(int, input().split(' '))

        if not done:
            if len(allowed_x) == 0 and len(allowed_y) == 0:
                allowed_x.append(x)
                allowed_y.append(y)
            elif x in allowed_x and y > max(allowed_y):
                allowed_y.remove(max(allowed_y))
                allowed_y.append(y)
            elif x in allowed_x and y < min(allowed_y):
                allowed_y.remove(min(allowed_y))
                allowed_y.append(y)
            elif y in allowed_y and x > max(allowed_x):
                allowed_x.remove(max(allowed_x))
                allowed_x.append(x)
            elif y in allowed_y and x < min(allowed_x):
                allowed_x.remove(min(allowed_x))
                allowed_x.append(x)
            elif len(allowed_x) == 1 and len(allowed_y) == 1:
                if x not in allowed_x:
                    allowed_x.append(x)
                if y not in allowed_y:
                    allowed_y.append(y)
            elif len(allowed_x) == 2 and len(allowed_y) == 1:
                if x not in allowed_x:
                    done = True
                    res = False
                elif y not in allowed_y:
                    allowed_y.append(y)
            elif len(allowed_x) == 1 and len(allowed_y) == 2:
                if y not in allowed_y:
                    done = True
                    res = False
                elif x not in allowed_x:
                    allowed_x.append(x)

            else:
                if x in allowed_x and y not in range(min(allowed_y), max(allowed_y)+1) or\
                 y in allowed_y and x not in range(min(allowed_x), max(allowed_x) + 1) or\
                    x not in allowed_x and y not in allowed_y:
                    done = True
                    res = False

    if res:
        print('YES')
    else:
        print('NO')