#include <iostream>
#include <cstdio>

using namespace std;

struct nod
{
    int inf;
    nod*a;
}*p[100001];

int a[100001],n,m;

void par(int k)
{
    a[k]=1;
    for(nod*c=p[k]; c!=NULL; c=c->a)
    {
        if(a[c->inf]==0)
            par(c->inf);
    }
}

int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);

    scanf("%d %d",&n,&m);

    int x,y;

    for(int i=1; i<=m; i++)
    {
        scanf("%d %d",&x,&y);
        nod*c=new nod;
        c->inf=x;
        c->a=p[y];
        p[y]=c;

        c=new nod;
        c->inf=y;
        c->a=p[x];
        p[x]=c;
    }

    m=0;

    /*for(int i=1;i<=n;i++)
    {
        cout<<i<<":   ";
        for(nod*c=p[i];c!=NULL;c=c->a)
            cout<<c->inf<<" ";
        cout<<endl;
    }*/

    for(int i=1; i<=n; i++)
        if(a[i]==0)
        {
            m++;
            par(i);
        }

    printf("%d",m);
    return 0;
}