program dsf1;
 var n,m,i,k,x,y,j:longint;
     a:array[1..1001,1..1001] of byte;
     viz:array[1..1001] of byte;
 procedure dsf(nod:longint);
 var i:longint;
 begin
 viz[nod]:=1;
 for i:=1 to n do if (viz[i]=0) and (a[nod,i]=1) then dsf(i);
 end;
begin
  assign(input,'dsf.in'); reset(input);
  assign(output,'dsf.out'); rewrite(output);
  readln(n,m);
  for i:=1 to n do for j:=1 to n do a[i,j]:=0;
  for i:=1 to m do
    begin
    readln(x,y);
    a[x,y]:=1;
    a[y,x]:=1;
    end;
  for i:=1 to n do viz[i]:=0;
  k:=0;
  for i:=1 to n do
    if viz[i]=0 then begin dsf(i); inc(k) end;
    writeln(k);
  close(output);
end.