Adjacency list representation of undirected graph in csharp

Csharp program for Adjacency list representation of undirected graph. Here problem description and explanation.

// Include namespace system
using System;
/*
    Csharp Program for 
    Undirected graph representation by using adjacency list 
*/
public class AjlistNode
{
	// Vertices node key
	public int id;
	public AjlistNode next;
	public AjlistNode(int id)
	{
		// Set value of node key
		this.id = id;
		this.next = null;
	}
}
public class Vertices
{
	public int data;
	public AjlistNode next;
	public AjlistNode last;
	public Vertices(int data)
	{
		this.data = data;
		this.next = null;
		this.last = null;
	}
}
public class Graph
{
	// Number of Vertices
	public int size;
	public Vertices[] node;
	public Graph(int size)
	{
		// Set value
		this.size = size;
		this.node = new Vertices[size];
		this.setData();
	}
	// Set initial node value
	public void setData()
	{
		if (this.size <= 0)
		{
			Console.WriteLine("\nEmpty Graph");
		}
		else
		{
			for (var index = 0; index < this.size; index++)
			{
				this.node[index] = new Vertices(index);
			}
		}
	}
	// Connect two nodes
	public void connect(int start, int last)
	{
		var edge = new AjlistNode(last);
		if (this.node[start].next == null)
		{
			this.node[start].next = edge;
		}
		else
		{
			// Add edge at the end
			this.node[start].last.next = edge;
		}
		// Get last edge 
		this.node[start].last = edge;
	}
	//  Handling the request of adding new edge
	public void addEdge(int start, int last)
	{
		if (start >= 0 && start < this.size && 
            last >= 0 && last < this.size)
		{
			this.connect(start, last);
			if (start == last)
			{
				// When self loop
				return;
			}
			this.connect(last, start);
		}
		else
		{
			// When invalid nodes
			Console.WriteLine("\nHere Something Wrong");
		}
	}
	public void printGraph()
	{
		if (this.size > 0)
		{
			// Print graph ajlist Node value
			for (var index = 0; index < this.size; ++index)
			{
				Console.Write("\nAdjacency list of vertex " + 
                              index + " :");
				var temp = this.node[index].next;
				while (temp != null)
				{
					// Display graph node 
					Console.Write("  " + this.node[temp.id].data);
					// Visit to next edge
					temp = temp.next;
				}
			}
		}
	}
	public static void Main(String[] args)
	{
		// 5 implies the number of nodes in graph
		var g = new Graph(5);
		// Connect node with an edge
		g.addEdge(0, 1);
		g.addEdge(0, 2);
		g.addEdge(0, 4);
		g.addEdge(1, 2);
		g.addEdge(1, 4);
		g.addEdge(2, 3);
		g.addEdge(3, 4);
		// print graph element
		g.printGraph();
	}
}

Output

Adjacency list of vertex 0 :  1  2  4
Adjacency list of vertex 1 :  0  2  4
Adjacency list of vertex 2 :  0  1  3
Adjacency list of vertex 3 :  2  4
Adjacency list of vertex 4 :  0  1  3