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# 0858. Mirror Reflection

<https://leetcode.com/problems/mirror-reflection>

## Description

There is a special square room with mirrors on each of the four walls. Except for the southwest corner, there are receptors on each of the remaining corners, numbered `0`, `1`, and `2`.

The square room has walls of length `p` and a laser ray from the southwest corner first meets the east wall at a distance `q` from the `0th` receptor.

Given the two integers `p` and `q`, return *the number of the receptor that the ray meets first*.

The test cases are guaranteed so that the ray will meet a receptor eventually.

**Example 1:**

![](https://s3-lc-upload.s3.amazonaws.com/uploads/2018/06/18/reflection.png)

```
**Input:** p = 2, q = 1
**Output:** 2
**Explanation:** The ray meets receptor 2 the first time it gets reflected back to the left wall.
```

**Example 2:**

```
**Input:** p = 3, q = 1
**Output:** 1
```

**Constraints:**

* `1 <= q <= p <= 1000`

## ac

```java
```