def SquareRoot (N):
    Guess = N / 2.0
    Quotient = N / Guess
    NewGuess = (Guess + Quotient) / 2.0

    while (abs(Guess - NewGuess) > 1.0e-15):
        #print (Guess, NewGuess)
        Guess = NewGuess
        Quotient = N / Guess
        NewGuess = (Guess + Quotient) / 2.0

    return NewGuess


def Distance (X1,Y1,X2,Y2):
    A = X2 - X1
    B = Y2 - Y1
    return SquareRoot(A*A + B*B)