#include <fstream>

using namespace std;

int m,n,x,y,nr,i,a[1001][2002];
bool sel[1001];
ifstream f("dfs.in");
   ofstream g("dfs.out");
void df(int x){
  int i;
  //g<<x;
  sel[x]=true;
  for(i=1;i<=n; ++i)
   if(a[x][i]==1 && !sel[i]){
      df(i);
   }
}
int main()
{
   f>>n>>m;
   nr=0;
   for(i=1;i<=m;++i){
     f>>x>>y;
     a[x][y]=a[y][x]=1;
   }

for(i=1; i<=n; ++i){
  if(sel[i]==false){df(i);nr++;}
   }
   g<<nr;
return 0;
}