using System;

using System.Collections.Generic;       

public class Graph

{

    int V;

    List<int>[] adj;

    public Graph(int v)

    {

        V = v;

        adj = new List<int>[v];

        for(int i=0; i < V; i++)

        {

            adj[i] = new List<int>();

        }

    }

    public void AddEdge(int src, int dest)

    {

        adj[src].Add(dest);

    }   

    public void TopologicalSort()

    {

        var visited = new bool[V];

        Stack<int> stack = new Stack<int>();

        for(int i = 0; i < V; i++)

        {

            dfs(i, stack, visited);

        }

        int count = stack.Count;

        for(int j=0; j < count; j++)

        {

            Console.Write(stack.Pop() + " ");

        }

    }   

    private void dfs(int i, Stack<int> stack, bool[] visited)

    {

        if(!visited[i])

        {

            visited[i] = true;          

            var children = adj[i];

            foreach(var child in children)

            {

                dfs(child, stack, visited);

            }

            stack.Push(i);

        }               

    }

}               

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Topological Sort: \n");

        Graph g = new Graph(6);

        g.AddEdge(5, 0);g.AddEdge(5, 2);g.AddEdge(2, 3);g.AddEdge(3, 1);

        g.AddEdge(4, 0);g.AddEdge(4, 1);

        g.TopologicalSort();

    }

}