#include <cstdio>
#include <vector>
#include <stack>
#include <bitset>
using namespace std;
const int MAX=1e5 + 14;
vector <int> gr[MAX];
stack <int> st;
bitset <MAX> viz;
void dfs(int nod)
{
	st.push(nod);
	while(!st.empty())
	{
		int cur=st.top();
		viz[cur]=1;
		if(gr[cur].empty())
		{
			st.pop();
		}
		else
		{
			st.push(gr[cur].back());
			gr[cur].pop_back();
		}
	}
}
int main(int argc, char const *argv[])
{
	freopen("dfs.in","r",stdin);
	freopen("dfs.out","w",stdout);
	int n,m;
	scanf("%d%d",&n,&m);
	for(int i=1; i<=m; i++)
	{
		int x,y;
		scanf("%d%d",&x,&y);
		gr[x].push_back(y);
		gr[y].push_back(x);
	}
	int num=0;
	for(int i=1; i<=n; i++)
	{
		if(!viz[i])
		{
			num++;
			dfs(i);
		}
	}
	printf("%d\n",num);
	return 0;
}