PROGRAMMING:Underground labyrinth exploration
Tunnel warfare was a way of fighting against Japanese invaders in the North China Plain during the Anti Japanese war. The underpass network is the underground works of house to house, street to street and village to village, as shown in the figure below.
While reviewing the arduous war life of our predecessors, we sincerely admire their intelligence. In today's era of peaceful development, for most people, exploring the underground passage may be just a kind of entertainment or educational game. This experimental case is to explore the underground passage maze as the content.
Suppose there is an underground passage labyrinth, its passages are straight, and there is a light and a switch on all the intersections (including the ends of the passage). How do you start from a certain starting point to light all the lights in the maze and return to the starting point?
###Input format:
The first line of input gives three positive integers, which respectively represent the number of nodes in the underground labyrinth $$n $$($$1 < n / Le 1000 $$, representing all intersections and endpoints of the channel), the number of edges $$M $$($$Le 3000 $$, representing the number of channels), and the number of exploration start nodes $$s $$(nodes from 1 to $$n $$). The next $$M $$row corresponds to the $$M $$edge (channel), and each row gives a pair of positive integers, which are the numbers of the two nodes directly connected by the edge.
###Output format:
If the lights of all nodes can be turned on, the sequence containing all nodes starting from $$s $$and ending with $$s $$will be output, and the adjacent nodes in the sequence must have edges (channels); Otherwise, although the lights of all nodes cannot be turned on, the node sequence that lights part of the lights is output, and finally 0 is output, which indicates that the labyrinth is not a connected graph.
Because the node sequence of depth first traversal is not unique, in order to make the output have unique results, we agree to access (light up) in the order of node small number priority. After lighting all the lights that can be lit, return to the starting point in the same way.
###Input sample 1:
```in
6 8 1
1 2
2 3
3 4
4 5
5 6
6 4
3 6
1 5
```
###Output sample 1:
```out
1 2 3 4 5 6 5 4 3 2 1
```
###Input sample 2:
```
6 6 6
1 2
1 3
2 3
5 4
6 5
6 4
```
###Output sample 2:
```
6 4 5 4 6 0
```
answer：If there is no answer, please comment
While reviewing the arduous war life of our predecessors, we sincerely admire their intelligence. In today's era of peaceful development, for most people, exploring the underground passage may be just a kind of entertainment or educational game. This experimental case is to explore the underground passage maze as the content.
Suppose there is an underground passage labyrinth, its passages are straight, and there is a light and a switch on all the intersections (including the ends of the passage). How do you start from a certain starting point to light all the lights in the maze and return to the starting point?
###Input format:
The first line of input gives three positive integers, which respectively represent the number of nodes in the underground labyrinth $$n $$($$1 < n / Le 1000 $$, representing all intersections and endpoints of the channel), the number of edges $$M $$($$Le 3000 $$, representing the number of channels), and the number of exploration start nodes $$s $$(nodes from 1 to $$n $$). The next $$M $$row corresponds to the $$M $$edge (channel), and each row gives a pair of positive integers, which are the numbers of the two nodes directly connected by the edge.
###Output format:
If the lights of all nodes can be turned on, the sequence containing all nodes starting from $$s $$and ending with $$s $$will be output, and the adjacent nodes in the sequence must have edges (channels); Otherwise, although the lights of all nodes cannot be turned on, the node sequence that lights part of the lights is output, and finally 0 is output, which indicates that the labyrinth is not a connected graph.
Because the node sequence of depth first traversal is not unique, in order to make the output have unique results, we agree to access (light up) in the order of node small number priority. After lighting all the lights that can be lit, return to the starting point in the same way.
###Input sample 1:
```in
6 8 1
1 2
2 3
3 4
4 5
5 6
6 4
3 6
1 5
```
###Output sample 1:
```out
1 2 3 4 5 6 5 4 3 2 1
```
###Input sample 2:
```
6 6 6
1 2
1 3
2 3
5 4
6 5
6 4
```
###Output sample 2:
```
6 4 5 4 6 0
```
answer：If there is no answer, please comment