#include <iostream>

#include <cstdio>

#include <cstring>

#include <cmath>

#include <algorithm>

#include <vector>

#include <stack>

#define mem(a, b) memset(a, b, sizeof(a))

using namespace std;

const int maxn = , INF = 0x7fffffff;

int dfn[maxn], low[maxn], drgee[maxn];

bool graph[][];

int dfs_clock, n, m, ret;

vector<int> G[maxn];

void init()

{

    for(int i=; i<=n; i++) G[i].clear();

    ret = ;

    dfs_clock = ;

    mem(low, );

    mem(dfn, );

    mem(drgee, );

    mem(graph, );

}

void tarjan(int u, int fa)

{

    dfn[u] = low[u] = ++dfs_clock;

    for(int i=; i<G[u].size(); i++)

    {

        int v = G[u][i];

        if(!dfn[v])

        {

            tarjan(v, u);

            low[u] = min(low[u], low[v]);

        }

        else if(v != fa)

        {

            low[u] = min(low[u], dfn[v]);

        }

    }

}

int main()

{

   while(cin>> n >> m){

    init();

    for(int i=; i<m; i++)

    {

        int u, v;

        cin>> u >> v;

        if(!graph[u][v])

        {

            graph[u][v] = graph[v][u] = ;

            G[u].push_back(v);

            G[v].push_back(u);

        }

    }

    tarjan(, -);

    for(int i=; i<=n; i++)

        for(int j=; j<G[i].size(); j++)

            if(low[i] != low[G[i][j]])

                drgee[low[i]]++;     //只统计low[i]  不统计low[G[i][j]]  以此保证了不会 重复统计

    for(int i=; i<=n; i++)

        if(drgee[i] == )

            ret++;

    cout<< (ret+)/ <<endl;

   }

    return ;

}