#!/usr/bin/python
# -*- coding: utf-8 -*-


import math


class Vec2D:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __add__(self, other):
        return Vec2D(self.x + other.x, self.y + other.y)

    def __sub__(self, other):
        return Vec2D(self.x - other.x, self.y - other.y)

    def __mul__(self, other):
        return self.x * other.x + self.y * other.y

    def __eq__(self, other):
        return self.x == other.x and self.y == other.y

    def __str__(self):
        return "(%g, %g)" % (self.x, self.y)

    def __abs__(self):
        return math.sqrt(self.x**2 + self.y**2)

    def __ne__(self, other):
        return not self.__eq__(other)  # reuse __eq__