#include <stdio.h>
#include <list>

using namespace std;

int n,m,viz[100001];
list<int> v[100001];

int mai_e()
{
    int i;
    for(i=1;i<=n;i++)
        if(viz[i]==0) return i;
    return 0;
}

void df(int x)
{
    viz[x]=1;
    list<int>::const_iterator itr,fin;
    itr=v[x].begin();
    fin=v[x].end();
    for(itr;itr!=fin;itr++)
        if(viz[*itr]==0) df(*itr);
}

int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    int i,x,y,comp_con=0;
    scanf("%d%d",&n,&m);
    for(i=0;i<m;i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    x=1;
    while(x!=0)
    {
        comp_con++;
        df(x);
        x=mai_e();
    }
    printf("%d",comp_con);

    return 0;
}