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: Accepted)

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


namespace AtCoder
{

    struct mint : IEquatable<mint>
    {
        //static uint mod = 998244353;
        static uint mod = 1000000007;
        uint _v;

        public mint(long v) : this((uint)(v % mod + mod)){ }
        private mint(uint v)
        {
            _v = v < mod ? v : (v - mod);
        }

        public static void SetMod(uint p)
        {
            mod = p;
        }

        public static mint operator+(mint lhs, mint rhs)
        {
            return new mint(lhs._v + rhs._v);
        }
        public static mint operator-(mint lhs, mint rhs)
        {
            return new mint(lhs._v + mod - rhs._v);
        }
        public static mint operator*(mint lhs, mint rhs)
        {
            return new mint((uint)((ulong)lhs._v * rhs._v % mod));
        }
        public static mint operator/(mint lhs, mint rhs)
        {
            return lhs * rhs.Inv();
        }
        public static mint operator^(mint x, int n)
        {
            return Pow(x, n);
        }
        public static bool operator==(mint l, mint r)
        {
            return l._v == r._v;
        }
        public static bool operator!=(mint l, mint r)
        {
            return !(l == r);
        }
        public static bool operator<(mint l, mint r)
        {
            return l._v < r._v;
        }
        public static bool operator>(mint l, mint r)
        {
            return l._v > r._v;
        }

        public static mint Pow(mint x, int n)
        {
            var r = new mint(1);
            while (n > 0)
            {
                if ((n & 1) > 0) r *= x;
                x *= x;
                n >>= 1;
            }
            return r;
        }
        
        public mint Pow(int n)
        {
            return Pow(this, n);
        }
        public mint Inv()
        {
            return Pow((int)mod - 2);
        }
        
        public bool Equals(mint o)
        {
            return this == o;
        }

        public override bool Equals(object obj)
        {
            if (obj is mint) return this == (mint)obj;
            else return false;
        }
        public override int GetHashCode()
        {
            return _v.GetHashCode();
        }
        public override string ToString()
        {
            return _v.ToString();
        }

        public static implicit operator mint(int i)
        {
            return new mint(i);
        }
        public static implicit operator mint(long i)
        {
            return new mint(i);
        }


        private static mint[] _fact;
        public static void SetFact(int n)
        {
            _fact = new mint[n + 1];
            _fact[0] = 1;
            for (int i = 1; i < n + 1; i++)
            {
                _fact[i] = _fact[i - 1] * i;
            }
        }
        public static mint Fact(int n)
        {
            if (_fact == null || _fact.Length < n)
            {
                SetFact(n * 2);
            }
            return _fact[n];
        }

        public static mint Combination(int n, int r)
        {
            return Fact(n) / (Fact(n - r) * Fact(r));
        }
    }
    static class Extensions
    {
        public static int LowerBound<T>(this IList<T> list, T value, IComparer<T> comp=null)
        {
            if (comp == null) comp = Comparer<T>.Default;

            var l = 0;
            var r = list.Count;

            while (l < r)
            {
                var m = (l + r) / 2;
                var c = comp.Compare(value, list[m]);
                if (c > 0) l = m + 1;
                else  r = m;
            }

            return l;
        }
        public static int UpperBound<T>(this IList<T> list, T value, IComparer<T> comp=null)
        {
            if (comp == null) comp = Comparer<T>.Default;

            var l = 0;
            var r = list.Count;

            while (l < r)
            {
                var m = (l + r) / 2;
                var c = comp.Compare(value, list[m]);
                if (c >= 0) l = m + 1;
                else r = m;
            }

            return r;
        }
    }
    class Program
    {
		static int ReadInt()
        {
            return int.Parse(Console.ReadLine());
        }
        static long ReadLong()
        {
            return long.Parse(Console.ReadLine());
        }
        static int[] ReadIntArray()
        {
            return Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        }
        static int[] ReadIntArray(int n)
        {
            var a = new int[n];
            for (int i = 0; i < n; i++)
            {
                a[i] = ReadInt();
            }
            return a;
        }
        static long[] ReadLongArray()
        {
            return Console.ReadLine().Split(' ').Select(long.Parse).ToArray();
        }
        static long[] ReadLongArray(int n)
        {
            var a = new long[n];
            for (int i = 0; i < n; i++)
            {
                a[i] = ReadLong();
            }
            return a;
        }
        static List<T> ReadObjects<T>(int n, Func<int[], T> creator)
        {
            var l = new List<T>(n);

            for (int i = 0; i < n; i++)
            {
                var a = ReadIntArray();
                l.Add(creator(a));
            }

            return l;
        }

        static int[,] ReadMatrix(int n, int m)
        {
            var r = new int[n, m];
            for (int i = 0; i < n; i++)
            {
                var a = ReadIntArray();
                for (int j = 0; j < m; j++)
                {
                    r[i, j] = a[j];
                }
            }
            return r;
        }
		
        public static int[] ZAlgotithm(string s)
        {
            var len = s.Length;

            var a = new int[len];
            a[0] = len;
            var i = 1;
            var j = 0;
            while (i < len)
            {
                while (i + j < len && s[j] == s[i + j]) j++;
                a[i] = j;

                if (j == 0)
                {
                    i++;
                    continue;
                }

                var k = 1;
                while (i + k < len && k + a[k] < j)
                {
                    a[i + k] = a[k];
                    k++;
                }
                i += k;
                j -= k;
            }

            return a;
        }
        public class MaxHeap<T> : IEnumerable<T>
        {
            private List<T> _list;
            private Comparer<T> _comp;
			
            public int Count
            {
                get
                {
                    return _list.Count;
                }
            }
            public MaxHeap() : this(0) { }
            public MaxHeap(int capacity, Comparison<T> comp=null)
            {
                _list = new List<T>(capacity);

                if (comp == null)
                {
                    _comp = Comparer<T>.Default;
                }
                else
                {
                    _comp = Comparer<T>.Create(comp);
                }
            }
            
            public void Push(T elem)
            {
                Upheap(elem);
            }

            public T Pop()
            {
                return Downheap();
            }

            public T Peek()
            {
                return _list[0];
            }

            
            private void Swap(int i, int j)
            {
                var a = _list[j];
                _list[j] = _list[i];
                _list[i] = a;
            }

            private void Upheap(T elem)
            {
                _list.Add(elem);
                var i = _list.Count - 1;

                while (true)
                {
                    if (i == 0) return;
                    var j = (i - 1) / 2;

                    var e = _list[i];
                    var p = _list[j];

                    var c = _comp.Compare(e, p);
                    if (c > 0)
                    {
                        Swap(i, j);
                        i = j;
                        continue;
                    }
                    else
                    {
                        break;
                    }
                }
            }

            private T Downheap()
            {
                var result = _list[0];

                var last = _list.Count - 1;
                Swap(0, last);
                _list.RemoveAt(last);
                if (_list.Count == 0) return result;

                var i = 0;
                while (true)
                {
                    if (i == _list.Count - 1) return result;
                    var p = _list[i];

                    var j = i * 2 + 1;
                    if (j >= _list.Count) return result;

                    if(j+1 < _list.Count && _comp.Compare(_list[j], _list[j+1]) < 0)
                    {
                        j++;
                    }

                    if (_comp.Compare(_list[i], _list[j]) < 0)
                    {
                        Swap(i, j);
                        i = j;
                    }
                    else
                    {
                        return result;
                    }
                }
            }
            public MaxHeap<T> Copy(Comparison<T> comp=null)
            {
                var c = new MaxHeap<T>(0, comp);
                c._list = _list.ToList();

                return c;
            }
            public MaxHeap(List<T> list)
            {
                _list = list;

                _comp = Comparer<T>.Default;
            }

            public List<T> GetList()
            {
                return _list;
            }

            public IEnumerator<T> GetEnumerator()
            {
                return _list.GetEnumerator();
            }

            IEnumerator IEnumerable.GetEnumerator()
            {
                return GetEnumerator();
            }
        }
		
        public class MinHeap<T> : IEnumerable<T>
        {
            private List<T> _list;
            private Comparer<T> _comp;

            public int Count
            {
                get
                {
                    return _list.Count;
                }
            }

            public MinHeap() : this(0) { }
            public MinHeap(int capacity, Comparison<T> comp = null)
            {
                _list = new List<T>(capacity);

                if (comp == null)
                {
                    _comp = Comparer<T>.Default;
                }
                else
                {
                    _comp = Comparer<T>.Create(comp);
                }
            }

            public void Push(T elem)
            {
                Upheap(elem);
            }

            public T Pop()
            {
                return Downheap();
            }

            public T Peek()
            {
                return _list[0];
            }


            private void Swap(int i, int j)
            {
                var a = _list[j];
                _list[j] = _list[i];
                _list[i] = a;
            }

            private void Upheap(T elem)
            {
                _list.Add(elem);
                var i = _list.Count - 1;

                while (true)
                {
                    if (i == 0) return;
                    var j = (i - 1) / 2;

                    var e = _list[i];
                    var p = _list[j];

                    var c = _comp.Compare(e, p);
                    if (c < 0)
                    {
                        Swap(i, j);
                        i = j;
                        continue;
                    }
                    else
                    {
                        break;
                    }
                }
            }

            private T Downheap()
            {
                var result = _list[0];

                var last = _list.Count - 1;
                Swap(0, last);
                _list.RemoveAt(last);
                if (_list.Count == 0) return result;

                var i = 0;
                while (true)
                {
                    if (i == _list.Count - 1) return result;
                    var p = _list[i];

                    var j = i * 2 + 1;
                    if (j >= _list.Count) return result;

                    if (j + 1 < _list.Count && _comp.Compare(_list[j], _list[j + 1]) > 0)
                    {
                        j++;
                    }

                    if (_comp.Compare(_list[i], _list[j]) > 0)
                    {
                        Swap(i, j);
                        i = j;
                    }
                    else
                    {
                        return result;
                    }
                }
            }

            public MinHeap<T> Copy(Comparison<T> comp = null)
            {
                var c = new MinHeap<T>(0, comp);
                c._list = _list.ToList();

                return c;
            }
            public MinHeap(List<T> list)
            {
                _list = list;

                _comp = Comparer<T>.Default;
            }

            public List<T> GetList()
            {
                return _list;
            }

            public IEnumerator<T> GetEnumerator()
            {
                return _list.GetEnumerator();
            }

            IEnumerator IEnumerable.GetEnumerator()
            {
                return GetEnumerator();
            }
        }
        class InputLine
        {
            private string[] _inputs;
            private int _index = 0;

            InputLine(string input)
            {
                _inputs = input.Split();
                _index = 0;
            }

            public static InputLine Read()
            {
                return new InputLine(Console.ReadLine());
            }

            public int NextInt()
            {
                return int.Parse(_inputs[_index++]);
            }
            public long NextLong()
            {
                return long.Parse(_inputs[_index++]);
            }
            public double NextDouble()
            {
                return double.Parse(_inputs[_index++]);
            }
        }
        public static int GCD(int x, int y)
        {
            var a = Math.Max(x, y);
            var b = x + y - a;

            while (b != 0)
            {
                var c = b;
                b = a % b;
                a = c;
            }

            return a;
        }
        public static long GCD(long x, long y)
        {
            var a = Math.Max(x, y);
            var b = x + y - a;

            while (b != 0)
            {
                var c = b;
                b = a % b;
                a = c;
            }

            return a;
        }
        static long ModPower(long x, long y, long mod)
        {
            var bytes = BitConverter.GetBytes(y);
            var bits = new System.Collections.BitArray(bytes);

            var max2 = 0;
            for (int i = bits.Length - 1; i >= 0; i--)
            {
                if (bits[i])
                {
                    max2 = i;
                    break;
                }
            }

            long result = 1;
            for (int i = max2; i >= 0; i--)
            {
                result = (result * result) % mod;
                if (bits[i])
                {
                    result = (result * x) % mod;
                }
            }

            return result;
        }
        
        static long ModFact(long n, long mod)
        {
            long result = 1;

            for (int i = 1; i <= n; i++)
            {
                result = result * i % mod;
            }
            return result;
        }
		
        static long ModAdd(long x, long y, long mod)
        {
            return ((x % mod) + (y % mod)) % mod;
        }
        static long ModMul(long x, long y, long mod)
        {
            return ((x % mod) * (y % mod)) % mod;
        }

        static long ModDiv(long x, long y, long mod)
        {
            //フェルマーの小定理より、a^(-1) = a^(p-2)
            return ModMul(x, ModPower(y, mod - 2, mod), mod);
        }
        static long ModComb(long n, long r, long mod)
        {
            long numerator = 1;
            for (int i = 0; i < r; i++)
            {
                numerator = ModMul(numerator, n - i, mod);
            }

            long denominator = ModFact(r, mod);

            return ModDiv(numerator, denominator, mod);
        }
        class Graph
        {
            private int _size;
            private List<int>[] _map;

            public IEnumerable<int> this[int i]
            {
                get
                {
                    if (_map[i] == null) return Enumerable.Empty<int>();
                    return _map[i];
                }
            }

            public Graph(int size)
            {
                _size = size;
                _map = new List<int>[size];
            }

            public void Add(int from, int to)
            {
                if (_map[from] == null)
                {
                    _map[from] = new List<int>();
                }
                _map[from].Add(to);
            }
        }
        class Graph<T>
        {
            private int _size;
            private List<T>[] _edges;

            public Graph(int size)
            {
                _size = size;
                _edges = new List<T>[size];
            }

            public List<T> this[int i]
            {
                get
                {
                    if (_edges[i] == null) _edges[i] = new List<T>();
                    return _edges[i];
                }
            }
        }
        static Graph<T> NewGraph<T>(int size, T template)
        {
            return new Graph<T>(size);
        }
        static List<T> NewList<T>(T template)
        {
            return new List<T>();
        }
        static T[] NewArray<T>(int size, T template)
        {
            return new T[size];
        }
        static long p1097 = 1000000007;
        static void Main(string[] args)
        {
			//↓


            var n = ReadInt();

            var bs = new int[n+1];
            var edges = new List<int>[n];

            for (int i = 1; i < n; i++)
            {
                var ab = ReadIntArray();
                var a = ab[0];
                var b = ab[1];
                bs[i] = b;
                if (edges[a] == null) edges[a] = new List<int>();
                edges[a].Add(b);
            }

            var rc = new int[n + 1];
            var k = 0;
            for (int i = 1; i < n; i++)
            {
                var e = edges[i];
                if (e == null) continue;

                var c = 0;
                foreach (var b in e)
                {
                    c++;
                    if (c == rc[i]) c++;
                    rc[b] = c;
                }

                k = Math.Max(k, c);
            }

            Console.WriteLine(k);
            for (int i = 1; i < n; i++)
            {
                Console.WriteLine(rc[bs[i]]);
            }

			//↑
        }

	}
}