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 Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Scanner;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class Main {
    private static final Map<Integer, Set<NodeIndex>> map = new HashMap<>();

    public static void main(final String[] args) {
        final FastScanner scanner = new FastScanner(System.in);
        final int n = scanner.nextInt();
        final int[] array = new int[n + 1];

        for (int i = 0; i < n - 1; i++) {
            final int a = scanner.nextInt();
            final int b = scanner.nextInt();

            map.computeIfAbsent(a, set -> new HashSet<>())
                    .add(new NodeIndex(b, i));
            map.computeIfAbsent(b, set -> new HashSet<>())
                    .add(new NodeIndex(a, i));
            array[a]++;
            array[b]++;
        }

        int maxValue = 0;
        int index = -1;
        for (int i = 0; i <= n; i++) {
            if (array[i] >= maxValue) {
                maxValue = array[i];
                index = i;
            }
        }

        final Set<Integer> set = IntStream.rangeClosed(1, maxValue)
                .boxed()
                .collect(Collectors.toSet());

        final int[] answer = new int[n - 1];
        recursive(set, index, -1, answer, -1);
        System.out.println(maxValue);
        for (final int i : answer) {
            System.out.println(i);
        }
    }

    private static void recursive(final Set<Integer> set, final int now, final int parent, final int[] answer, final int hen) {
        final Set<NodeIndex> nodeIndices = map.get(now);
        final List<Integer> list = set.stream()
                .filter(h -> h != hen)
                .collect(Collectors.toList());
        int index = 0;
        for (final NodeIndex nodeIndex : nodeIndices) {
            if (nodeIndex.node == parent) {
                continue;
            }

            final Integer value = list.get(index);
            answer[nodeIndex.index] = value;
            recursive(set, nodeIndex.node, now, answer, value);
            index++;
        }
    }

    static class NodeIndex {
        final int node;
        final int index;

        NodeIndex(final int node, final int index) {
            this.node = node;
            this.index = index;
        }
    }



    static class FastScanner {
        private final BufferedReader reader;
        private StringTokenizer tokenizer;

        FastScanner(final InputStream in) {
            reader = new BufferedReader(new InputStreamReader(in));
            tokenizer = null;
        }

        String next() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        String nextLine() {
            if (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    return reader.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }

            return tokenizer.nextToken("\n");
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }
    }
}