Types: n: int, w: int, h: int, r: int, v_x: int, v_y: int, x_i: int, y_i: int
Ranges: 2 ≤ n ≤ 11, 4 ≤ w, h ≤ 1,000, 1 ≤ r ≤ 100, -10,000 ≤ v_x, v_y ≤ 10,000 and (v_x, v_y) ≠ (0, 0), r < x_i < w - r, r < y_i < h - r
Addtl Info: The number of datasets is less than 100. The end of the input is indicated by a line containing a single zero. When r changes by eps (eps < 10^{-9}), the ball which collides first and the way of the collision do not change.