There are two objects A, B on a line and a wall is placed at left. A is closer than B to the wall. Initially, A and B are static and each has 1 kg, $n$ kg. Suddenly, B moves toward A with speed 1 m/s and collides. The collision is elastic.
input parameter: a positive integer $n$ ($n \le 10^6$)
return value: the collision number between A and B or A and wall
Hint: When two objects with mass $m_1$ and $m_2$ collide with the initial velocity (not speed) $v_{1i}$ and $v_{2i},ドル the final velocity $v_{1f}$ and $v_{2f}$ satisfy the equation $m_{1}v_{1i} + m_{2}v_{2i} = m_{1}v_{1f} + m_{2}v_{2f}$. And in elastic collision, the kinetic energy is conserved.