#include <cstdio>
#include <cstring>

using namespace std;

FILE *fin=freopen("dfs.in","r",stdin);
FILE *fout=freopen("dfs.out","w",stdout);

int n,m,viz[100000];

struct nod
{
    int inf;
    nod *urm;
}*a[100000];

void add(nod*&q, int inf)
{
    nod *p= new nod;
    p->inf=inf;
    p->urm=q;
    q=p;
}

void citire()
{
    scanf("%d %d",&n,&m);
    int x,y;
    while(m--)
    {
        scanf("%d %d",&x,&y);
        add(a[x],y);
        add(a[y],x);
    }
}

void dfs(nod *p,int v)
{
    for(nod *i=p;i;i=i->urm)
        if(!viz[i->inf])
        {
            viz[i->inf]=v;
            dfs(a[i->inf],v);
        }
}

int main()
{
    citire();
    int nr=0;
    for(int p=1;p<=n;p++){
        if(viz[p]==0){
            viz[p]=p;
            dfs(a[p],p);
            nr++;
        }
    }
    printf("%d\n",nr);
    return 0;
}