# include <vector>
# include<stdio.h>
using namespace std;
vector <int> v[100010];
int i,n,x,y,m,nr;
bool viz[100010];
void df(int i)
{
	viz[i]=true;
	for ( vector <int> :: iterator it=v[i].begin(); it!=v[i].end(); it++)
	{
		if (viz[*it]==false)
			df(*it);
	}
}
int main()
{
	freopen("dfs.in","r",stdin);
	freopen("dfs.out","w",stdout);
	scanf("%d %d\n",&m,&n);
	for (i=1; i<=m; i++)
	{
		scanf("%d %d\n",&x,&y);
		v[x].push_back(y);
		v[y].push_back(x);
	}
	for (i=1; i<=n; i++)
		viz[i]=false;
	for (i=1; i<=n; i++)
		if (viz[i]==false) { df(i); nr++; }
	printf("%d\n",nr);
	return 0;
	
}