//#define debug //*******************************************************************************************************************************************
#ifdef debug
#include <chrono>
#endif

#include <iostream>
#include <algorithm> // next_permutation
#include <iomanip>
#include <cmath>
#include <vector>
#include <sstream>
#include <string>
#include <cstring> //memcpy
#include <cstdio>
#include <stack>
#include <queue>
#include <list>
#include <numeric> //accumulate
//#include <map>
//#include <unordered_map> //hash func.
#include <fstream> //ifstream, ofstream

//#define NDEBUG //If NDEBUG is defined before #include <cassert>, assert will be ignored. You had better define NDEBUG when u submit the code.
#include <cassert> //assert

using namespace std;


#define dout cout
//If u wanna output to a text file instead of standard output, plz define OUTPUTFILE.
//#define OUTPUTFILE "output.txt" //*******************************************************************************************************************************************
#ifdef OUTPUTFILE
#define dout outputfile
ofstream outputfile(OUTPUTFILE);
#define OutputFilePath "/Users/Nag/Documents/Prgm/Test/DerivedData/Test/Build/Products/Debug/output.txt"
#endif


#define din cin
//If u wanna input from a text file instead of standard input, plz define INPUTFROMTEXTFILEを.
//#define INPUTFILE "input.txt" //*******************************************************************************************************************************************
#ifdef INPUTFILE
#define din inputfile
ifstream inputfile(INPUTFILE);
#endif

#define scan(A) scanf("%d", &(A))
#define disp(A) dout << #A << " = " << setw(3) << (A) << endl
#define disP(A) dout << setw(3) << (A) << " "
#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define dispAll(A,n) dout << #A << " = "; rep(j, 0, (n)) {disP(A[j]);} dout << endl
//#define dispAll(A,n) cout << #A << " = "; rep(j, 0, (n)) {cout << setw(3) << A[j] << " ";} cout << endl

#define sign(x) ((x)>0)-((x)<0) //x<0: -1, x=0: 0, x>0: +1
#define p(i) (i)/2
#define l(i) (i)*2
#define r(i) (i)*2+1

typedef pair<int,int> pii;
typedef vector<int> vi;
typedef long long ll;

const int INF = 2e9+10;
const ll INF_LL = 1e18; //Be careful for overflow.
const int NONE = -1;
const ll MOD = 1e9+7;

const int N_MAX = 1e5+10; //num of vertex or element
const int M_MAX = 100000; //num of edge
const int DATA_MAX = 1000000010;

int N;
int root[51];
int M;
vector<pii> E; //set of edge


int find(int x) {
    if(root[x]==x) return x;
    else return root[x] = find(root[x]);
}

#define unite(x,y) root[find(x)] = find(y)
#define isSame(x,y) (find(x)==find(y))



void display() {
    
    dout << "----\n";
    rep(i,0,E.size()) {
        disP(i); dout << " : " << E[i].first << " --- " << E[i].second << endl;
    }
    dout << "----\n";
    dout << "   i = "; rep(i,0,N+1) disP(i); dout<<endl;
    dispAll(root, N+1);
    dout << "----\n";
}



int main() {
    //------------------------------------------------------------------------------------------
#ifdef debug
    //start timer
    auto startTime = chrono::system_clock::now();
#endif
    //------------------------------------------------------------------------------------------
    
    //cin, coutの高速化  ＊注意：cinを使うなら全部cinで、scanfを使うなら全部scanfで統一するように！
    cin.tie(0); //cinとcoutの同期を切る
    ios::sync_with_stdio(false); //iostreamとstdioの同期を切る
    
    //read input data
    din >> N >> M;
    int a, b;
    rep(i,0,M) {
        din >> a >> b;
        E.push_back(make_pair(a, b));
    }
    
    
#ifdef debug
    display();
#endif
    
    
    //calc.
    int ans = 0;
    rep(i,0,E.size()) {
        
        //initialize root[]
        rep(k,1,N+1) {
            root[k] = k;
        }
        
        //check if E[i] is bridge or not
        rep(j,0,E.size()) {
            if(i==j) continue;
            
            unite(E[j].first, E[j].second);
        }
        
        
#ifdef debug
        display();
        disp(i);
        disp(E[i].first);
        disp(E[i].second);
#endif
        
        if( isSame(E[i].first, E[i].second) ) {
#ifdef debug
            dout << "this is NOT a bridge.\n";
#endif
        }
        else {
            ans++;
#ifdef debug
            dout << "this is a birdge!!\n";
#endif
        }
        
        
    
#ifdef debug
        dout << "   i = "; rep(i,0,N+1) disP(i); dout<<endl;
        dispAll(root, N+1);
        
        dout << "\n\n\n\n---------------------------------------------\n\n\n";
#endif
    }
    
    
#ifdef debug
    dout << "ans = ";
#endif
    dout << ans << endl;
    
    
    
    
    
    //------------------------------------------------------------------------------------------
#ifdef debug
    //stop timer
    auto endTime = chrono::system_clock::now();
    auto dur = endTime - startTime;
    auto msec = chrono::duration_cast<chrono::milliseconds>(dur).count();
    dout << fixed << setprecision(4) << (double)msec/1000 << " sec \n";
#endif
    //------------------------------------------------------------------------------------------
    
#ifdef INPUTFILE
    inputfile.close();
#endif
    
#ifdef OUTPUTFILE
    outputfile.close();
    cout << "\"" << OutputFilePath << "\"" << endl;
#endif
    
    return 0;
}

Measured memory_bytes: 256