---

import math
import random
import tkinter as tk

W, H = 800, 600
root = tk.Tk()
canvas = tk.Canvas(root, width=W, height=H, bg="black")
canvas.pack()

mouse = [-1000, -1000]

def on_move(e):
    mouse[0] = e.x
    mouse[1] = e.y

canvas.bind("<Motion>", on_move)

circles = []
for _ in range(random.randint(5, 15)):
    r = random.randint(15, 50)
    x = random.randint(r, W - r)
    y = random.randint(r, H - r)
    color = "#%02x%02x%02x" % (random.randint(50, 255), random.randint(50, 255), random.randint(50, 255))
    item = canvas.create_oval(x - r, y - r, x + r, y + r, fill=color, outline="")
    circles.append({
        "id": item,
        "x": x,
        "y": y,
        "vx": random.choice([-1, 1]) * random.uniform(1, 4),
        "vy": random.choice([-1, 1]) * random.uniform(1, 4),
        "r": r,
    })

def update():
    mx, my = mouse
    for c in circles:
        c["x"] += c["vx"]
        c["y"] += c["vy"]

        if c["x"] < c["r"]:
            c["x"] = c["r"]
            c["vx"] = abs(c["vx"])
        elif c["x"] > W - c["r"]:
            c["x"] = W - c["r"]
            c["vx"] = -abs(c["vx"])
        if c["y"] < c["r"]:
            c["y"] = c["r"]
            c["vy"] = abs(c["vy"])
        elif c["y"] > H - c["r"]:
            c["y"] = H - c["r"]
            c["vy"] = -abs(c["vy"])

        dx = c["x"] - mx
        dy = c["y"] - my
        d = math.hypot(dx, dy)
        if 0 < d < c["r"]:
            nx, ny = dx / d, dy / d
            dot = c["vx"] * nx + c["vy"] * ny
            if dot < 0:
                c["vx"] -= 2 * dot * nx
                c["vy"] -= 2 * dot * ny
            c["x"] = mx + nx * c["r"]
            c["y"] = my + ny * c["r"]

        canvas.coords(c["id"], c["x"] - c["r"], c["y"] - c["r"], c["x"] + c["r"], c["y"] + c["r"])

    root.after(16, update)

update()
root.mainloop()