static void Main()
{
int numberOfFriends = int.Parse(Console.ReadLine());
int leadDancer = int.Parse(Console.ReadLine());
Tree dancers = new Tree(new TreeNode(leadDancer));
// create tree of friends
for (int i = 0; i < numberOfFriends; i++)
{
string[] friendship = Console.ReadLine().Split(' ');
int firstPerson = int.Parse(friendship[0]);
int secondPerson = int.Parse(friendship[1]);
TreeNode firstPersonNode = dancers.FindNodeByValue(firstPerson);
TreeNode secondPersonNode = dancers.FindNodeByValue(secondPerson);
if (firstPersonNode == null)
{
firstPersonNode = new TreeNode(firstPerson);
}
if (secondPersonNode != null)
{
firstPersonNode.AddFriend(secondPersonNode);
}
else
{
TreeNode presentSecondPerson = new TreeNode(secondPerson);
firstPersonNode.AddFriend(presentSecondPerson);
}
}
int longestPath = BFS(dancers.GetRoot());
Console.WriteLine(longestPath);
}
private static int BFS(TreeNode node)
{
Queue<TreeNode> queue = new Queue<TreeNode>();
int longestPath = 0;
queue.Enqueue(node);
while (queue.Count > 0)
{
TreeNode currentNode = queue.Dequeue();
foreach (TreeNode friend in currentNode.Friends)
{
queue.Enqueue(friend);
}
longestPath++;
}
return longestPath;
}
public bool IsFriendOf(TreeNode check)
{
return this.Friends.Contains(check);
}
public void AddFriend(TreeNode friend)
{
this.Friends.Add(friend);
friend.Friends.Add(this);
}
