#include<bits/stdc++.h>

using namespace std;

#define MAXN 5010

#define MAXM 10010

struct edge

{

        int to,nxt;

} e[MAXM << ];

int i,n,m,cnt,s,timer,tot;

int head[MAXN],u[MAXM],v[MAXM],low[MAXN],dfn[MAXN],belong[MAXN],degree[MAXN];

bool is_bridge[MAXM << ];

inline void addedge(int u,int v)

{

        tot++;

        e[tot] = (edge){v,head[u]};

        head[u] = tot;

}

inline void tarjan(int u,int t)

{

        int i,v;

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

        for (i = head[u]; i; i = e[i].nxt)

        {

                v = e[i].to;

                if (!dfn[v])

                {

                        tarjan(v,i);

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

                        if (low[v] > dfn[u])

                                is_bridge[i] = is_bridge[i ^ ] = true;

                }    else if (i != (t ^ )) low[u] = min(low[u],dfn[v]);

        }

}

inline void dfs(int u)

{

        int i,v;

        belong[u] = cnt;

        for (i = head[u]; i; i = e[i].nxt)

        {

                v = e[i].to;

                if (!belong[v] && !is_bridge[i])

                        dfs(v);

        }

}

int main()

{

        scanf("%d%d",&n,&m);

        tot = ;

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

        {

                scanf("%d%d",&u[i],&v[i]);

                addedge(u[i],v[i]);

                addedge(v[i],u[i]);

        }

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

        {

                if (!dfn[i])

                        tarjan(i,);

        }

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

        {

                if (!belong[i])

                {

                        cnt++;

                        dfs(i);

                }

        }

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

        {

                if (belong[u[i]] != belong[v[i]])

                {

                        degree[belong[u[i]]]++;

                        degree[belong[v[i]]]++;

                }

        }

        for (i = ; i <= cnt; i++) s += (degree[i] == );

        printf("%d\n",(s + ) / );

        return ;

}