##### input
```
8 9
1 2 4 8 16 32 64 128
1 2
2 3
3 4
2 5
3 6
7 4
4 1
1 8
8 2
```
##### output
```
239
```
by dbg_8 @ 2023-03-22 11:49:59
@[dbg_8](/user/244245) 这组样例我过了，可还是爆0 QAQ~~~
（~~验证码aqqq祭~~）
by wuyueton @ 2023-03-22 21:15:24
感谢样例
by Aaronwrq @ 2023-08-14 10:39:39