#include <fstream>
#define NMAX 100001
#include <vector>
using namespace std;
ifstream f("dfs.in");
ofstream g("dfs.out");
vector <int> a[NMAX];
int i,j,n,m,x,y,comp[NMAX],k,l[NMAX];
void fadfs(int x)
{
    int i;
    for(i=0;i<l[x];i++)
    {
        if(comp[a[x][i]]==0) { comp[a[x][i]]=k; fadfs(a[x][i]); }
    }
}
int main()
{
    f>>n>>m;
    for(i=1;i<=m;i++)
    {
        f>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    k=0;
    for(i=1;i<=n;i++) l[i]=a[i].size();
    for(i=1;i<=n;i++)
        if(comp[i]==0) { comp[i]=++k; fadfs(i);}
    g<<k;
    return 0;
}