In a social network, online communities refer to the group of people with an interest towards the same topic.
People connect with each other in a social network. A connection between Person I and Person J is represented as C I J. When two persons belonging to different communities connect, the net effect is merger of both communities which I and J belonged to.
We are only interested in finding out the communities with the member count being an even number. Your task is to find out those communities.