#include<stdio.h>
#include<vector.h>
#include<algorithm>
#include<bitset>
#include<queue>
using namespace std;
#define dim 101000
struct nod
{
    int el;
    nod *next;

}*liste[dim];
int n,m;
bitset<dim> viz;
queue<int>q;
inline void add(int x , int y )
{
    nod *p=new nod;
    p->el=y;
    p->next=liste[x];
    liste[x]=p; return;
}
void read()
{
    int x,y;
    scanf("%d %d",&n,&m);
    for(int i=1 ; i<=m;i++)
    {
        scanf("%d %d",&x,&y);
        add(x,y);
        add(y,x);
    }
}
inline void bf(int x)
{
    nod *p=liste[x];

    for(q.push(x) ; !q.empty(); q.pop())
    {
        x = q.front();
        p=liste[x];
         while (p)
    {
        if ( viz[p->el]==0 )
        {
            viz[p->el]=1;
            q.push(p->el);
        }
        p=p->next;
    }
    }
}
void solve ()
{
    int nr=0;
    for(int i=1 ; i<=n;i++)
    {
        if ( viz[i] == 0 )
        {
            bf (i);
            nr++;
        }
    }
    printf("%d ",nr);
}
int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    read();
    solve();
    return 0;
}