Consider an adjacency-list based undirected graph type. Devise a linear-time algorithm to count the parallel edges in the undirected graph. Implement your algorithm in C++ and demonstrate how it works on the following undirected graph:

13

17

0 5

4 3

0 1

8 7

9 12

6 4

7 8

5 4

0 2

11 12

12 9

9 10

0 6

7 8

9 11

5 3

5 0