def calculate_unit_vector(x0, y0, x1, y1):
    length = ((x1 - x0) ** 2 + (y1 - y0) ** 2) ** 0.5
    ux = (x1 - x0) / length
    uy = (y1 - y0) / length
    return ux, uy

print(
    "This program calculates the unit vector between "
    "two points on a 2-dimensional plane."
)
initial_x = float(input("Input starting point x coordinate: "))
initial_y = float(input("Input starting point y coordinate: "))
target_x = float(input("Input target point x coordinate: "))
target_y = float(input("Input target point y coordinate: "))
unit_x, unit_y = calculate_unit_vector(
    initial_x, initial_y, target_x, target_y
)
print("Unit vector (x y):", unit_x, unit_y)