Language: C++

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace Competitive
{
    internal class Node
    {
        public List <Edge> Edges;
        public int Dist;
        public int No;
        public bool Visited;
        public int Start;
        public int End;

        public Node(int no)
        {
            this.No = no;
            Dist = int.MaxValue;
            Edges = new List<Edge>();
            Visited = false;
        }
    }

    internal class Edge
    {
        public int From;
        public int To;
        public int Cost;
       

        public Edge(int fr, int to, int cost = 0)
        {
            From = fr;
            To = to;
            Cost = cost;
        }

    }

    internal class Graph
    {
        public List<Node> Nodes;

        public Node this[int i]
        {
            set { Nodes[i] = value; }
            get { return Nodes[i]; }
        }

        public Graph(int N)
        {
            Nodes = new List<Node>();
            for (int i = 0; i < N; i++)
            {
                Nodes.Add(new Node(i));
            }
        }

    }

    internal class Solution
    {
        public int N;
        public Graph G;
        public int T;

        public void Run()
        {
            N = Input.ReadInt();
            G = new Graph(N);
            
            for (int i = 0; i < N; i++)
            {
                var line = Input.ReadIntArray();
                var o = line[1];
                for (int j = 0; j < o; j++)
                {
                    int fr = i;
                    int to = line[2 + j] - 1;
                    G[i].Edges.Add(new Edge(fr, to));
                }
            }

            RunGraph();
            for (int i = 0; i < N; i++)
            {
                Console.WriteLine("{0} {1} {2}", i, G[i].Start, G[i].End);
            }
        }

        public void RunGraph()
        {
            T = 0;
            for (int i = 0; i < N; i++)
                DFS(i);

        }

        public void DFS(int i)
        {
            if (G[i].Visited) return;
            T++;
            G[i].Start = T;
            G[i].Visited = true;
            foreach (var e in G[i].Edges)
            {
                DFS(e.To);
            }

            T++;
            G[i].End = T;
        }

    }

    
    internal static class Input
    {
        public static int ReadInt()
        {
            string line = Console.ReadLine();
            return int.Parse(line);
        }

        public static int[] ReadIntArray()
        {
            string line = Console.ReadLine();
            return line.Split(' ').Select(int.Parse).ToArray();            
        }

        public static double[] ReadDoubleArray()
        {
            string line = Console.ReadLine();
            return line.Split(' ').Select(double.Parse).ToArray();
        }
    }
    
    internal class Program
    {
        public static void Main(string[] args)
        {
            var s = new Solution();
            s.Run();
        }
    }
}


Compiler output:
a.cc:1:7: error: expected nested-name-specifier before 'System'
    1 | using System;
      |       ^~~~~~
a.cc:2:7: error: expected nested-name-specifier before 'System'
    2 | using System.Collections.Generic;
      |       ^~~~~~
a.cc:3:7: error: expected nested-name-specifier before 'System'
    3 | using System.Linq;
      |       ^~~~~~
a.cc:4:7: error: expected nested-name-specifier before 'System'
    4 | using System.Web;
      |       ^~~~~~
a.cc:8:5: error: 'internal' does not name a type
    8 |     internal class Node
      |     ^~~~~~~~
a.cc:26:5: error: 'internal' does not name a type
   26 |     internal class Edge
      |     ^~~~~~~~
a.cc:42:5: error: 'internal' does not name a type
   42 |     internal class Graph
      |     ^~~~~~~~
a.cc:63:5: error: 'internal' does not name a type
   63 |     internal class Solution
      |     ^~~~~~~~
a.cc:119:5: error: 'internal' does not name a type
  119 |     internal static class Input
      |     ^~~~~~~~
a.cc:140:5: error: 'internal' does not name a type
  140 |     internal class Program
      |     ^~~~~~~~