#include <iostream>
#include <fstream>
using namespace std;
int a[2000][2000],viz[1000],nr,n;
void asd (int x)
{
    viz[x]=1;
    for (int i=1;i<=n;i++)
         if (viz[i]==0 && a[x][i]!=0)
            asd(i);

}
int main()
{
    ifstream cin ("dfs.in");
    ofstream cout ("dfs.out");
    int m,i,x,y;
    cin>>n;cin>>m;
   for (i=1;i<=m;i++)
    {
        cin>>x;cin>>y;
        a[x][y]=1;
        a[y][x]=1;

    }
    for (i=1;i<=n;i++)
    {
        if (viz[i]==0)
            {asd (i);nr++;}
    }
    cout<<nr;

    return 0;
}