def main():
    # parse number of queries
    q = int(raw_input().strip())
    
    # go over each query
    for _ in xrange(q):
        # parse points and store coordinates
        n, points, res = int(raw_input().strip()), list(), True
        cx, cy = list(), list()
        for _ in xrange(n):
            x, y = map(int, raw_input().strip().split())
            cx.append(x)
            cy.append(y)
      
        # minimum, maximum
        min_x, max_x = min(cx), max(cx)
        min_y, max_y = min(cy), max(cy)
    
        # check coordinates
        res = True
        for i in xrange(n):
            if cx[i] != min_x and cx[i] != max_x:
                if cy[i] != min_y and cy[i] != max_y:
                    res = False
                    break
            elif cy[i] < min_y or cy[i] > max_y:
                res = False
                break

        # final result
        print("YES" if res else "NO") 


if __name__ == "__main__":
    main()