from math import *
import numpy as np

def main():

    #initialisation
    x1 = np.array([0, 0, 0])
    x2 = np.array([1, 0, 0])
    x3 = np.array([1, 0, 0])

    v1 = np.array([0, 0, 0])
    v2 = np.array([1, 0, 0])
    v3 = np.array([1, 0, 0])



if __name__ == '__main__':
    main()