ZOJ Problem Set - 4131
A "$k$-hour clock" is a day keeping method which follows the rules below:
We know that it's $x$ o'clock now, and after $y$ hours it will be $z$ o'clock. What's the value of $k$?
There are multiple test cases. The first line of the input is an integer $T$ (about $10^5$), indicating the number of test cases. For each test case:
The first and only line contains three integers $x$, $y$ and $z$ ($0 \le x, z \le 10^9$, $1 \le y \le 10^9$).
For each test case output one line containing one integer, indicating the value of $k$. Note that there must be $1 \le k \le 2 \times 10^9$. If there are multiple valid answers, you can print any of them; If there is no valid answer, print "-1" (without quotes) instead.
4 11 18 5 3 49 4 1 9 1 1 3 10
12 24 3 -1
Author: WENG, Caizhi
Source: The 2019 ICPC China Shaanxi Provincial Programming Contest