#include<fstream>
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
int viz[1000000],a[2000000][2000000],n,m;
void df(int k)
{
	int j;
	viz[k]=1;
	for(j=1;j<=n;j++)
		if(a[k][j]&&viz[j]==0)
			df(j);
}
int main()
{
	int x,y,k=0,i;
	f>>n>>m;
	for( i=1;i<=m;i++)
		f>>x>>y,a[x][y]=a[y][x]=1;
	for( i = 1; i<=n; i++)
    {
        if(!viz[i])
            df(i),k++;
    }
    g << k << "\n";
    return 0;
}