#include<bits/stdc++.h>
using namespace std;
int n,m,x,y,low[50005],pre[50005],scc[50005],scc_time,scc_cnt;
vector<int>a[50005];
stack<int>S;
inline int read()
{
	char ch;
	int r=0;
	while(!('0'<=ch&&ch<='9'))
	ch=getchar();
	while('0'<=ch&&ch<='9')
	{
		r=r*10+ch-'0';
		ch=getchar();
	}
	return r;
}
inline void dfs(int x)
{
	pre[x]=low[x]=++scc_time; 
	S.push(x);
	for(int i=0;i<a[x].size();i++)
	{
		int u=a[x][i];
		if(!pre[u]){
			dfs(u);
			low[x]=min(low[u],low[x]);
		}
		else if(!scc[u])low[x]=min(low[x],pre[u]);
	}
	if(pre[x]==low[x])
	{
		scc_cnt++;
		for(;;)
		{
			int v=S.top();
			S.pop();
			scc[v]=scc_cnt;
			if(v==x)break;
		}
	}
}
int main()
{
	freopen("religion.in","r",stdin);
	freopen("religion.out","w",stdout);
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++)
	{
		int x=read();
		int y=read();
		a[x].push_back(y);
		a[y].push_back(x);
	}
	for(int i=1;i<=n;i++)
	if(!pre[i])dfs(i);
	cout<<scc_cnt;
	return 0;
}