#include <iostream>
#include <vector>
#include <fstream>
#include <cmath>

using namespace std;

const int _SIZE = 200002;

struct edg
{
    int to, num;
    edg () {}
    edg(int _to, int _num)
    {
        to = _to;
        num = _num;
    }
};

int n, m, timer, timer_in[_SIZE], fup[_SIZE], color[_SIZE];
bool is_bridge[_SIZE], used[_SIZE], used2[_SIZE];
vector<vector<edg > > g;
vector<vector<int > > bridges, new_g;

void find_bridges(int from, int parent = -1)
{
    used[from] = 1;
    timer_in[from] = fup[from] = timer++;
    for (int i = 0; i < g[from].size(); ++i)
    {
        int to = g[from][i].to;
        if (to == parent)//для петелек
            continue;
        if (used[to])//если были в следующей вершине
            fup[from] = min(fup[from], timer_in[to]);// то чситаем сколько до верха, до текущей
        else
        {
            find_bridges(to, from);
            fup[from] = min(fup[from], fup[to]);
            if (fup[to] > timer_in[from])
            {
                int freq = 0;
                bool f = 0;
                for (int j = 1; j <= n; ++j)
                {
                    if (j == from)
                        for (int k = 0; k <= g[j].size(); ++k)
                        {
                            if(g[j][k].to == to)
                                freq++;
                            if(freq == 2)
                            {
                                f = 1;
                                break;
                            }
                        }
                    if(f)
                        break;
                }
                if(!f)
                {
                    is_bridge[g[from][i].num] = 1;
                    bridges[from].push_back(to);
                    bridges[to].push_back(from);
                }
            }
        }
    }
}

void fill_point(int from)
{
    color[from] = from;
    used2[from] = 1;
    for (int i = 0; i < g[from].size(); ++i)
    {
        int to = g[from][i].to;
        if(!is_bridge[g[from][i].num] && !used2[to])
        {
            color[to] = from;
            used2[to] = 1;
            fill_point(to);
        }
    }
}

int main()
{
    //ifstream cin("input.txt");
    cin >> n >> m;
    g.resize(n + 1);
    bridges.resize(n + 1);
    new_g.resize(n + 1);
    for (int i = 0; i < m; ++i)
    {
        int from, to;
        cin >> from >> to;
        g[from].push_back(edg(to, i));
        g[to].push_back(edg(from, i));
    }
    timer = 0;
    for (int i = 1; i <= n; ++i)
        if (!used[i])
            find_bridges(i);
    for (int i = 1; i <= n; ++i)
        if (!used2[i])
            fill_point(i);
    for (int i = 1; i <= n; ++i)
        for (int j = 0; j < g[i].size(); ++j)
            if (is_bridge[g[i][j].num])
                new_g[color[i]].push_back(color[g[i][j].to]);
    int ans = 0;
    for (int i = 1; i <= n; ++i)
        if (new_g[i].size() == 1)
            ++ans;
    cout << ceil(ans / 2);
    return 0;
}

    int to, num;
    edg () {}
    edg(int _to, int _num)
    {
        to = _to;
        num = _num;
    }
};

int n, m, timer, timer_in[_SIZE], fup[_SIZE], color[_SIZE];
bool is_bridge[_SIZE], used[_SIZE], used2[_SIZE];
vector<vector<edg > > g;
vector<vector<int > > bridges, new_g;

void find_bridges(int from, int parent = -1)
{
    used[from] = 1;
    timer_in[from] = fup[from] = timer++;
    for (int i = 0; i < g[from].size(); ++i)
    {
        int to = g[from][i].to;
        if (to == parent)//для петелек
            continue;
        if (used[to])//если были в следующей вершине
            fup[from] = min(fup[from], timer_in[to]);// то чситаем сколько до верха, до текущей
        else
        {
            find_bridges(to, from);
            fup[from] = min(fup[from], fup[to]);
            if (fup[to] > timer_in[from])
            {
                is_bridge[g[from][i].num] = 1;
                bridges[from].push_back(to);
                bridges[to].push_back(from);
            }
        }
    }
}

void fill_point(int from)
{
    color[from] = from;
    used2[from] = 1;
    for (int i = 0; i < g[from].size(); ++i)
    {
        int to = g[from][i].to;
        if(!is_bridge[g[from][i].num])
        {
            if (!used2[to])
            {
                color[to] = from;
                fill_point(to);
                used2[to] = 1;
            }
        }
    }
}

int main()
{
    ifstream cin("input.txt");
    cin >> n >> m;
    g.resize(n + 1);
    bridges.resize(n + 1);
    new_g.resize(n + 1);
    for (int i = 0; i < m; ++i)
    {
        int from, to;
        cin >> from >> to;
        g[from].push_back(edg(to, i));
        g[to].push_back(edg(from, i));
    }
    timer = 0;
    for (int i = 1; i <= n; ++i)
        if (!used[i])
            find_bridges(i);
    for (int i = 1; i <= n; ++i)
        if (!used2[i])
            fill_point(i);
    for (int i = 1; i <= n; ++i)
        for (int j = 0; j < g[i].size(); ++j)
            if (is_bridge[g[i][j].num])
                new_g[color[i]].push_back(color[g[i][j].to]);
    int ans = 0;
    for (int i = 1; i <= n; ++i)
        if (new_g[i].size() == 1)
            ++ans;
    cout << ans;
    return 0;
}