#include <stdio.h>
#include <vector>
#define NMAX 100005
#define pb push_back
using namespace std;
int n,m,rez;
vector <int> A[NMAX];
bool viz[NMAX];
void read()
{
	scanf("%d%d",&n,&m);
	int i,x,y;
	for (i=1; i<=m; i++)
	{
		scanf("%d%d",&x,&y);
		A[x].pb(y); A[y].pb(x);
	}
}
void dfs(int nod)
{
	int i,vec;
	for (i=0; i<A[nod].size(); i++)
	{
		vec=A[nod][i];
		if (!viz[vec]) {
			viz[vec] = true;
			dfs(vec);
		}
	}
}
void solve()
{
	int i;
	for (i=1; i<=n; i++)
		if (!viz[i]) {
			viz[i] = true;
			dfs(i),rez++;
		}
}
int main()
{
	freopen("dfs.in","r",stdin);
	freopen("dfs.out","w",stdout);
	read();
	solve();
	printf("%d\n",rez);
	return 0;
}