#include <cstdio>
#include <vector>
using namespace std;
vector <int> g[100010];
int nr,n,m;
int viz[100010];
void citire()
{
    scanf("%d %d",&n,&m);
    int x,y;
    for(int i=0;i<m;i++)
    {
        scanf("%d %d",&x,&y);
        g[x].push_back(y);
        g[y].push_back(x);
    }
}
void latime(int v)
{
    viz[v]=1;
    for(int i=0;i<g[v].size();i++)
    {
        int q=g[v][i];
        if(viz[q]==0)
            latime(q);
    }
}
void prelucrare()
{
    for(int i=1;i<=n;i++)
    {
        if(viz[i]==0)
        {
            nr++;
            latime(i);
        }
    }
}
int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    citire();
    prelucrare();
    printf("%d\n",nr);
    return 0;
}