#include<cstdio>
#include<vector>
std::vector<int> v[200001];
bool vizitat[100001];
void DFS(int nod)
{
 for(int i=0;i<v[nod].size();i++)
     {
      if(!vizitat[v[nod][i]])
         vizitat[v[nod][i]]=true,DFS(v[nod][i]);
     }
}
int main()
{
 freopen("dfs.in","r",stdin);
 freopen("dfs.out","w",stdout);
 int n,m;
 scanf("%d %d ",&n,&m);
 for(int i=1;i<=m;i++)
     {
      int x,y;
      scanf("%d %d ",&x,&y);
      v[x].push_back(y);
      v[y].push_back(x);
     }
 int componente_conexe=1;
 DFS(1);
 for(int i=2;i<=n;i++)
     {
      if(!vizitat[i])
         DFS(i),componente_conexe++;
     }
 printf("%d ",componente_conexe);
fclose(stdin);
fclose(stdout);
return 0;
}