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, coada:array[1..Nmax] of longint;
    t:array[0..1, 1..2*Mmax] of longint;
    i, j, k, contor, n, m:longint;
procedure bfs(nod:longint);
var p, u, z:longint;
begin
   p := 1; u := 1;
   viz[nod] := true; coada[p] := nod;
   while p <= u do
      begin
         z := start[coada[p]];
         while z <> 0 do
            begin
               if not(viz[t[0, z]]) then
                  begin
                     inc(u);
                     coada[u] := t[0, z];
                     viz[t[0, z]] := true;
                  end;
               z := t[1, z];
            end;
         inc(p);
      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);
               bfs(k);
            end;
      end;
   writeln(g, contor);
   close(f); close(g);
end.