var t:array[1..1000,1..1000] of integer;
    n,m,i,j,a,b,nr:integer;
    viz:array[1..1000] of integer;
procedure dfs(nod:integer);
var j:integer;
begin
 viz[nod]:=1;
 for j:=1 to n do
  if (t[nod][j]=1) and (viz[j]=0) then dfs(j);
end;
begin
 assign(input,'dfs.in');
 reset(input);
 readln(n,m);
 for i:=1 to m do
  begin
   readln(a,b);
   t[a][b]:=1;
   t[b][a]:=1;
  end;
  close(input);

  assign(output,'dfs.out');
  rewrite(output);
  for i:=1 to n do
   if viz[i]=0 then
    begin
     dfs(i);
     nr:=nr+1;
    end;
  writeln(nr);
  close(output);
end.