/**************************************************************

     Problem: 1718

     User: rausen

     Language: C++

     Result: Accepted

     Time:44 ms

     Memory:3148 kb

 ****************************************************************/

 #include <cstdio>

 #include <cstring>

 #include <algorithm>

 using namespace std;

 const int N = 5e4 + ;

 const int M = 1e5 + ;

 struct edge {

     int next, to;

     edge(int _n = , int _t = ) : next(_n), to(_t) {}

 } e[M];

 int n, m, ans;

 int cnt, top, num, tot = ;

 int dfn[N], low[N], vis[N], sz[N], s[N], w[N], first[N];

 int mp[N];

 inline void Add_Edges(int x, int y) {

     e[++tot] = edge(first[x], y), first[x] = tot;

     e[++tot] = edge(first[y], x), first[y] = tot;

 }

 void DFS(int p, int from) {

     dfn[p] = low[p] = ++cnt;

     s[++top] = p, vis[p] = ;

 #define y e[x].to

     register int x;

     for (x = first[p]; x; x = e[x].next)

         if (x != (from ^ )) {

             if (!vis[y]) DFS(y, x);

             if (vis[y] < ) low[p] = min(low[p], low[y]);

         }

 #undef y

     if (dfn[p] == low[p]) {

         register int y;

         ++num;

         while (s[top + ] != p) {

             y = s[top--];

             vis[y] = , w[y] = num;

             ++sz[num];

         }

     }

 }

 inline void tarjan() {

     int i;

     cnt = top = num = ;

     memset(vis, sizeof(vis), );

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

         if (!vis[i]) DFS(i, );

 }

 int main() {

     int i, x, y;

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

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

         scanf("%d%d", &x, &y);

         Add_Edges(x, y);

     }

     tarjan();

 #define y e[x].to

     memset(mp, , sizeof(mp));

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

         for (x = first[i]; x; x = e[x].next)

             if (w[i] != w[y]) ++mp[w[y]];

     for (ans = i = ; i <= num; ++i)

         ans += (mp[i] == );

     printf("%d\n", ans >> );

 #undef y

     return ;