class Point:
    def __init__(self, x, y, index):
        self.x = x
        self.y = y
        self.index = index

    def distance(self, point):
        return ((self.x - point.x)**2 + (self.y - point.y)**2)**0.5

    def __repr__(self):
        return "Point P" + str(self.index) + "(" + str(self.x) + ", " + str(self.y) + ")"

def orientation(p1, p2, p3):
    return (p2.y - p1.y)*(p3.x - p2.x) - (p3.y - p2.y)*(p2.x - p1.x)

def check_convex_quadrilateral(points):
    negative_angle_found = False
    positive_angle_found = False

    p1 = points[-2]
    p2 = points[-1]
    for i in range(len(points)):
        new_point = points[i]
        if orientation(p1, p2, new_point) > 0:
            positive_angle_found = True
        else:
            negative_angle_found = True

        p1 = p2
        p2 = new_point

        if positive_angle_found == negative_angle_found:
            return False

    return True



def isOnCircle(point, r):
    # Compare radius of circle with distance of its center from given point
    if (point.x - r.x)**2 + (point.y - r.y)**2 == 0:
        print("On the circle")
        return True
    else:
        point("Isn't on circle")
        return False

def position(point, r):
    if point.x**2 + point.y**2 - r == 0:
        print("On circle")
    elif point.x**2 + point.y**2 - r > 0:
        print("Outside")
    else:
        print("Inside")


#Check if a polygon is convex -- complexity: O(n)
def main():
    points = []
    count = 0
    with open("points.txt") as fin:
        for line in fin:
            input = []
            input.append([int(x) for x in line.split()])
            points.append(Point(input[0][0], input[0][1], count))
            count = count + 1
    fin.close()

    #Part I: Check if a quadrilateral is convex:
    if check_convex_quadrilateral(points) == True:
        print("The quadrilateral is convex")
        #Part II: Position of A4 for the triangle circumscribed about a circle

    else:
        print("The quadrilateral is not convex")



if __name__ == '__main__':
    main()