Two Rabbits

题意翻译

- 有一条数轴，上面有两只兔子。 - 一只兔子位于 $x$ 坐标，每秒跳 $a$ 个单位，另一只位于 $y$ 坐标，每秒跳 $b$ 个单位，保证 $x<y$ ，两只兔子相向而行。 - 请你求出两只兔子是否会在整数秒相遇，如果是，打印出相遇的那一秒（初始时间从 $0$ 开始），如果无法在整数秒相遇，则输出 `-1` 。 - translate by @[ShineEternal](https://www.luogu.com.cn/user/45475)。

题目描述

Being tired of participating in too many Codeforces rounds, Gildong decided to take some rest in a park. He sat down on a bench, and soon he found two rabbits hopping around. One of the rabbits was taller than the other. He noticed that the two rabbits were hopping towards each other. The positions of the two rabbits can be represented as integer coordinates on a horizontal line. The taller rabbit is currently on position $ x $ , and the shorter rabbit is currently on position $ y $ ( $ x \lt y $ ). Every second, each rabbit hops to another position. The taller rabbit hops to the positive direction by $ a $ , and the shorter rabbit hops to the negative direction by $ b $ . For example, let's say $ x=0 $ , $ y=10 $ , $ a=2 $ , and $ b=3 $ . At the $ 1 $ -st second, each rabbit will be at position $ 2 $ and $ 7 $ . At the $ 2 $ -nd second, both rabbits will be at position $ 4 $ . Gildong is now wondering: Will the two rabbits be at the same position at the same moment? If so, how long will it take? Let's find a moment in time (in seconds) after which the rabbits will be at the same point.

输入输出格式

输入格式

Each test contains one or more test cases. The first line contains the number of test cases $ t $ ( $ 1 \le t \le 1000 $ ). Each test case contains exactly one line. The line consists of four integers $ x $ , $ y $ , $ a $ , $ b $ ( $ 0 \le x \lt y \le 10^9 $ , $ 1 \le a,b \le 10^9 $ ) — the current position of the taller rabbit, the current position of the shorter rabbit, the hopping distance of the taller rabbit, and the hopping distance of the shorter rabbit, respectively.

输出格式

For each test case, print the single integer: number of seconds the two rabbits will take to be at the same position. If the two rabbits will never be at the same position simultaneously, print $ -1 $ .

输入输出样例

输入样例 #1

5
0 10 2 3
0 10 3 3
900000000 1000000000 1 9999999
1 2 1 1
1 3 1 1

输出样例 #1

2
-1
10
-1
1

说明

The first case is explained in the description. In the second case, each rabbit will be at position $ 3 $ and $ 7 $ respectively at the $ 1 $ -st second. But in the $ 2 $ -nd second they will be at $ 6 $ and $ 4 $ respectively, and we can see that they will never be at the same position since the distance between the two rabbits will only increase afterward.