#include <cstdio>
#include <vector>


using namespace std;

vector <int> a[100005];


int coada[110000],viz[100005],g[110000],prim,ultim,x,y,n,m,vfi,nr;


void dfs(int vf)
{
    if(prim==ultim)
        return;
    for(int i=0;i<g[vf];i++)
    {
        if(viz[a[vf][i]]==0)
        {
            viz[a[vf][i]]=1;
            coada[ultim]=a[vf][i];
            ultim++;
        }
    }
    prim++;
    dfs(coada[prim]);
}


int main()
{
    freopen("dfs.in","r",stdin);
    freopen("dfs.out","w",stdout);
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
    {
        viz[i]=0;
    }
    for(int i=1;i<=m;i++)
    {
        scanf("%d%d",&x,&y);
        a[x].push_back(y);
        a[y].push_back(x);
        g[x]++;
        g[y]++;
    }
    nr=0;
    for(int i=1;i<=n;i++)
    {
        if(viz[i]==0)
        {
            ultim=1;
            prim=0;
            dfs(i);
            nr++;
        }
    }
    printf("%d",nr);

    return 0;
}