Mojtaba is a police commander. A thief wants to escape. Mojtaba is standing at 0, The thief is standing at X on the x-axis. The thief starts to run with speed $v_B$ to right, and Mojtaba starts to cache him with speed $v_A$. When he catches the thief, he comes back to 0 with speed $v_A$, how much time it takes from Mojtaba to cache the thief and back to the police station?

Your answer will be considered correct if the absolute difference between the jury solution and your solution is $< 10^{-6}$

Input Format

The first line contains three space separated integers $X ,v_a , v_b , 0 \le X \le 100, 1 \le v_a,v_B \leq 100$ -- the position of the thief, speed of Mojtaba and speed of thief.

Output Format

Print how much time it takes from Mojtaba to cache the thief and back to the police station. Your answer will be considered correct if the absolute difference between the jury solution and your solution is $< 10^{-6} .$ If Mojtaba can never catch thief, print $-1$

( Output like $-1.000000...$  are okay )