This test could help you.

5 8 1 5
2 200
1 2 1 100 99
2 3 0 0 0
3 2 0 0 0
2 4 0 0 0
4 2 0 0 0
3 4 0 0 0
4 3 0 0 0
4 5 1 100 99

You can draw this graph on paper, and the answer will be obvious. I have this output:
99
3
1 4 8

Good luck.

I got RE9.I got WA10 after use your test.So interesting.QAQ
Sorry my bad English.

Edited by author 17.08.2021 06:35

In my case WA 10 was caused by one directional roads, not <->.
"In a country, there is a number of cities connected by unidirectional roads"