#include<fstream>
using namespace std;
ifstream fin("dfs.in");
ofstream fout("dfs.out");
int n,m,s;
struct nod
{
    int val;
    nod *nxt;
} *v[100010];
bool a[100010];
void citire()
{
    nod *p;
    int x,y;
    fin>>n>>m;
    for(int a1=1;a1<=n;a1++)
    {
        p=new(nod);
        p->val=0;
        v[a1]=p;
    }
    for(int a1=1;a1<=m;a1++)
    {
        fin>>x>>y;
        p=new(nod);
        p->val=y;
        p->nxt=v[x];
        v[x]=p;
        p=new(nod);
        p->val=x;
        p->nxt=v[y];
        v[y]=p;
    }
}
void fct(int x)
{
    nod *p;
    p=v[x];
    while(p->val)
    {
        if(a[p->val]==0)
        {
            a[p->val]=1;
            fct(p->val);
        }
        p=p->nxt;
    }
}
int main()
{
    citire();
    for(int a1=1;a1<=n;a1++)
    {
        if(a[a1]==0)
        {
            s++;
            fct(a1);
        }
    }
    fout<<s;
}