/**

 problem: http://poj.org/problem?id=3177

 tarjan blog: https://blog.csdn.net/reverie_mjp/article/details/51704523

 v 为下一结点， u为当前结点

 如果low[v] > dfn[u] 则 边(u,v)为桥

 缩点后剩下的所有边都为桥（缩点后即为树结构）

 将叶子结点相连使其成为双联通分量为最优解

 所以：

 添加(leaf + 1) / 2 条边即可使图成为双联通图

 **/

 #include<stdio.h>

 #include<stack>

 #include<algorithm>

 using namespace std;

 class Graphics{

     const static int MAXN = ;

     const static int MAXM =  * ;

 private:

     struct Edge{

         int to, next;

         bool bridge;

     }edge[MAXM];

     struct Point{

         int dfn, low, color;

     }point[MAXN];

     int first[MAXN], sign, sumOfPoint, dfnNum, colorNum;

     bool vis[MAXN];

     stack<int> stk;

     void tarjan(int u, int preEdge = -){

         point[u].low = dfnNum;

         point[u].dfn = dfnNum ++;

         vis[u] = true;

         stk.push(u);

         for(int i = first[u]; i != -; i = edge[i].next){

             int to = edge[i].to;

             if((i^) == preEdge) continue; /// 由于是双向边，防止由该边跑回原来的点

             if(!point[to].dfn){

                 tarjan(to, i);

                 point[u].low = min(point[u].low, point[to].low);

                 if(point[to].low > point[u].dfn){

                     edge[i].bridge = true;

                     edge[i^].bridge = true;

                 }

             }else if(vis[to]){

                 point[u].low = min(point[to].dfn, point[u].low);

             }

         }

         if(point[u].dfn == point[u].low){

             vis[u] = false;

             point[u].color = ++ colorNum;

             while(stk.top() != u){

                 point[stk.top()].color = colorNum;

                 vis[stk.top()] = false;

                 stk.pop();

             }

             stk.pop();

         }

     }

 public:

     void init(int n){

         sumOfPoint = n;

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

             first[i] = -;

             vis[i] = ;

         }

         sign = colorNum = ;

         dfnNum = ;

     }

     void addEdgeOneWay(int u, int v){

         edge[sign].to = v;

         edge[sign].next = first[u];

         edge[sign].bridge = false;

         first[u] = sign ++;

     }

     void addEdgeTwoWay(int u, int v){

         addEdgeOneWay(u, v);

         addEdgeOneWay(v, u);

     }

     void tarjanAllPoint(){

         for(int i = ; i <= sumOfPoint; i ++){

             if(!point[i].dfn)

                 tarjan(i);

         }

     }

     int getAns(){

         int *degree = new int[sumOfPoint+];

         int ans = ;

         for(int i = ; i <= sumOfPoint; i ++){

             degree[i] = ;

         }

         tarjanAllPoint();

         for(int i = ; i <= sumOfPoint; i ++){

             for(int j = first[i]; j != -; j = edge[j].next){

                 int to = edge[j].to;

                 if(edge[j].bridge){

                     degree[point[to].color] ++;

                 }

             }

         }

         for(int i = ; i <= sumOfPoint; i ++){

             if(degree[i] == ){

                 ans ++;

             }

         }

         delete []degree; return (ans + ) / ;

     }

 }graph;

 int main(){

     int f, r;

     scanf("%d%d", &f, &r);

     graph.init(f);

     while(r --){

         int a, b;

         scanf("%d%d", &a, &b);

         graph.addEdgeTwoWay(a, b);

     }

     printf("%d\n", graph.getAns());

     return ;

 }