The output: the results need to be saved to the happyVertices_output.txt text file:
One line contains the list of happy vertices of the undirected graph in ascending format, each number
separated by one comma.

If the undirected graph doesn't have any happy vertex, the result file will contain the message "All
of the vertices are isolated vertices".
Sample Input 1
Sample Output 1
99
0 1
0 2
5 of 5
05
1 7
2 3
2 4
3 4
4 5
Paper No: 1
0,1,2,3,4,5,7