Challenge: Implement Depth First Search

Problem Statement

You have to implement the Depth First Search algorithm on a graph using the data structures which we have implemented in the previous sections.

Note: Your solution should work for both connected and unconnected graphs.

Input

A graph in the form of an adjacency list

Note: You can start the traversal from any vertex.

Output

A string containing the vertices of the graph listed in the correct order of traversal.

Sample Input

Graph:

Vertex	Edges
0	None
1	3, 2
2	5, 4
3	None
4	None
5	None

Sample Output

"0124536" or "0136254" or "1362540" or "1362540"