atcoder#ABC168D. [ABC168D] .. (Double Dots)
[ABC168D] .. (Double Dots)
Score: points
Problem Statement
There is a cave.
The cave has rooms and passages. The rooms are numbered to , and the passages are numbered to . Passage connects Room and Room bidirectionally. One can travel between any two rooms by traversing passages. Room is a special room with an entrance from the outside.
It is dark in the cave, so we have decided to place a signpost in each room except Room . The signpost in each room will point to one of the rooms directly connected to that room with a passage.
Since it is dangerous in the cave, our objective is to satisfy the condition below for each room except Room .
- If you start in that room and repeatedly move to the room indicated by the signpost in the room you are in, you will reach Room after traversing the minimum number of passages possible.
Determine whether there is a way to place signposts satisfying our objective, and print one such way if it exists.
Constraints
- All values in input are integers.
- One can travel between any two rooms by traversing passages.
Input
Input is given from Standard Input in the following format:
Output
If there is no way to place signposts satisfying the objective, print No
.
Otherwise, print lines. The first line should contain Yes
, and the -th line should contain the integer representing the room indicated by the signpost in Room .
4 4
1 2
2 3
3 4
4 2
Yes
1
2
2
If we place the signposts as described in the sample output, the following happens:
- Starting in Room , you will reach Room after traversing one passage: . This is the minimum number of passages possible.
- Starting in Room , you will reach Room after traversing two passages: . This is the minimum number of passages possible.
- Starting in Room , you will reach Room after traversing two passages: . This is the minimum number of passages possible.
Thus, the objective is satisfied.
6 9
3 4
6 1
2 4
5 3
4 6
1 5
6 2
4 5
5 6
Yes
6
5
5
1
1
If there are multiple solutions, any of them will be accepted.