using System;
using System.Text;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using static System.Console;
using static System.Math;

namespace AtCorder
{
    class Program
    {
        static void Main(string[] args)
        {
            new Program().Solve(new ConsoleInput(Console.In, ' '));
        }


        public void Solve(ConsoleInput cin)
        {
            var N = cin.ReadInt;
            var M = cin.ReadInt;
            var a = new int[M];
            var b = new int[M];
            var Matrix = new int[N, N];
            var ans = 0;
            for (int i = 0; i < M; i++)
            {
                a[i] = cin.ReadInt;
                b[i] = cin.ReadInt;
                Matrix[a[i] - 1, b[i] - 1] = 1;
                Matrix[b[i] - 1, a[i] - 1] = 1;
            }
            var flag = new bool[N];
            Action<int> dfs = null;
            dfs = (int v) =>
            {
                flag[v - 1] = true;
                for (int i = 0; i < N; i++)
                {
                    if (Matrix[v - 1, i] == 0 || flag[i])
                    {
                        continue;
                    }
                    dfs(i + 1);
                }
                return;
            };
            for (int i = 0; i < M; i++)
            {
                var isBirdge = false;
                for (int j = 0; j < N; j++)
                {
                    flag[j] = false;
                }
                Matrix[a[i] - 1, b[i] - 1] = 0;
                Matrix[b[i] - 1, a[i] - 1] = 0;
                dfs(1);
                for (int j = 0; j < N; j++)
                {
                    if (!flag[j])
                    {
                        isBirdge = true;
                        break;
                    }
                }
                if (isBirdge) ans++;
                Matrix[a[i] - 1, b[i] - 1] = 1;
                Matrix[b[i] - 1, a[i] - 1] = 1;
            }
            WriteLine(ans);
        }

        public class ConsoleInput
        {
            private readonly System.IO.TextReader _stream;
            private char _separator = ' ';
            private Queue<string> inputStream;
            public ConsoleInput(System.IO.TextReader stream, char separator = ' ')
            {
                this._separator = separator;
                this._stream = stream;
                inputStream = new Queue<string>();
            }
            public string Read
            {
                get
                {
                    if (inputStream.Count != 0) return inputStream.Dequeue();
                    string[] tmp = _stream.ReadLine().Split(_separator);
                    for (int i = 0; i < tmp.Length; ++i)
                        inputStream.Enqueue(tmp[i]);
                    return inputStream.Dequeue();
                }
            }
            public string ReadLine { get { return _stream.ReadLine(); } }
            public int ReadInt { get { return int.Parse(Read); } }
            public long ReadLong { get { return long.Parse(Read); } }
            public double ReadDouble { get { return double.Parse(Read); } }
            public string[] ReadStrArray(long N) { var ret = new string[N]; for (long i = 0; i < N; ++i) ret[i] = Read; return ret; }
            public int[] ReadIntArray(long N) { var ret = new int[N]; for (long i = 0; i < N; ++i) ret[i] = ReadInt; return ret; }
            public long[] ReadLongArray(long N) { var ret = new long[N]; for (long i = 0; i < N; ++i) ret[i] = ReadLong; return ret; }
        }
    }
}


Measured memory_bytes: 13268