program repet2;
const Nmax = 100005;
      Mmax = 200005;
var f, g:text;
    bufin, bufout:array[1..1 shl 16] of byte;
    viz:array[1..Nmax] of boolean;
    start:array[1..Nmax] of longint;
    t:array[0..1, 1..2*Mmax] of longint;
    i, j, k, contor, n, m:longint;
procedure dfs(nod:longint);
var z : longint;
begin
    viz[nod] := true;
    z := start[nod];
    while z <> 0 do
       begin
          if not(viz[t[0, z]]) then dfs(t[0, z]);
          z := t[1, z];
       end;
end;
begin
   assign(f, 'dfs.in'); reset(f);
   assign(g, 'dfs.out'); rewrite(g);
   settextbuf(f, bufin); settextbuf(f, bufout);
   readln(f, n, m); contor := 0;
   for k := 1 to m do
      begin
         readln(f, i, j);
         t[0, k * 2 - 1] := j;
         t[1, k * 2 - 1] := start[i];
         start[i] := k * 2 - 1;
         t[0, k * 2] := i;
         t[1, k * 2] := start[j];
         start[j] := k * 2;
      end;
   for k := 1 to n do
      begin
         if not(viz[k]) then
            begin
               inc(contor);
               dfs(k);
            end;
      end;
   writeln(g, contor);
   close(f); close(g);
end.