Problem:
Score : 400 points

Problem Statement

Given is a tree G with N vertices.
The vertices are numbered 1 through N, and the i-th edge connects Vertex a_i and Vertex b_i.

Consider painting the edges in G with some number of colors.
We want to paint them so that, for each vertex, the colors of the edges incident to that vertex are all different.

Among the colorings satisfying the condition above, construct one that uses the minimum number of colors.

Constraints

2 \le N \le 10^5

1 \le a_i \lt b_i \le N

All values in input are integers.

The given graph is a tree.

Input

Input is given from Standard Input in the following format:

N
a_1 b_1
a_2 b_2
\vdots
a_{N-1} b_{N-1}

Output

Print N lines.

The first line should contain K, the number of colors used.

The (i+1)-th line (1 \le i \le N-1) should contain c_i, the integer representing the color of the i-th edge, where 1 \le c_i \le K must hold.

If there are multiple colorings with the minimum number of colors that satisfy the condition, printing any of them will be accepted.

Sample Input 1

3
1 2
2 3

Sample Output 1

2
1
2

Sample Input 2

8
1 2
2 3
2 4
2 5
4 7
5 6
6 8

Sample Output 2

4
1
2
3
4
1
1
2

Sample Input 3

6
1 2
1 3
1 4
1 5
1 6

Sample Output 3

5
1
2
3
4
5

Solution in C# (Mono 4.6.2.0) (judge verdict: Runtime Error)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharp_AtCoder
{

    class EdgePair
    {
        public int a;
        public int b;
        public EdgePair(int a, int b)
        {
            this.a = a;
            this.b = b;
        }
    }
    
    class Program
    {

        static bool[] visit;

        static void Solve(int N, List<int>[] g, EdgePair[] edge_pairs)
        {
            int K = 0;  //使用する色の数
            int[,] edge_color = new int[N, N];
            List<int>[] having_color = new List<int>[N];
            for (int i = 0; i < N; i++) having_color[i] = new List<int>();
            Queue<int> q = new Queue<int>();
            q.Enqueue(0);
            HashSet<int> set = new HashSet<int>();

            //BFSの処理
            while(q.Count != 0)
            {
                int from = q.Dequeue();
                visit[from] = true;

                foreach(var to in g[from])
                {
                    if (!visit[to])
                    {
                        q.Enqueue(to);
                        int f_t_color = 1;  //from - toの辺の色
                        foreach(var color in having_color[from].OrderBy(x => x))
                        {
                            if(f_t_color != color)
                            {
                                break;
                            }
                            else
                            {
                                f_t_color++;
                            }
                        }

                        having_color[from].Add(f_t_color);
                        having_color[to].Add(f_t_color);
                        edge_color[from, to] = f_t_color;
                        edge_color[to, from] = f_t_color;
                        set.Add(f_t_color);

                    }
                }
            }

            //表示
            K = set.Count();
            Console.WriteLine("K:" + K);
            for(int i = 0; i < N - 1; i++)
            {
                int a = edge_pairs[i].a;
                int b = edge_pairs[i].b;
                Console.WriteLine(edge_color[a, b]);
            }
            
        }

       
        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());
            List<int>[] g = new List<int>[N];
            for (int i = 0; i < N; i++) g[i] = new List<int>();
            EdgePair[] edge_pairs = new EdgePair[N];
            visit = new bool[N];

            for(int i = 1; i < N; i++)
            {
                int[] input = Console.ReadLine().Split(' ').Select(x => int.Parse(x) - 1).ToArray();
                int a = input[0];
                int b = input[1];
                g[a].Add(b);
                g[b].Add(a);
                edge_pairs[i - 1] = new EdgePair(a, b);
            }

            Solve(N, g, edge_pairs);
        }
    }
}