const
    MAXN = 100000;
    MAXM = 100000;

var
    top, used: array [1..MAXN] of Integer;
    e, next: array [1..MAXN + 2 * MAXM + 1] of Integer;
    i, cur, v, n, m, a, b, nf, ans: Integer;

procedure addEdge(a, b: Integer);
begin
    e[top[a]] := b;
    next[top[a]] := nf;
    top[a] := nf;
    Inc(nf);
end;

procedure dfs(v: Integer);
var
    cur: Integer;
begin
    used[v] := 1;
    cur := v;
    while e[cur] <> -1 do begin
        if used[e[cur]] = 0 then
            dfs(e[cur]);
        cur := next[cur];
    end;
end;

begin
    ReadLn(n, m);
    nf := n + 1;
    for i := 1 to MAXN + 2 * MAXM + 1 do
        e[i] := -1;
    for i := 1 to n do begin
        top[i] := i;
        used[i] := 0;
    end;
    for i := 1 to m do begin
        ReadLn(a, b);
        addEdge(a, b);
        addEdge(b, a);
    end;
    ans := 0;
    for i := 1 to n do
        if used[i] = 0 then begin
            dfs(i);
            Inc(ans);
        end;
    WriteLn(ans);
end.