program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
    n, otv, i, k, left, right: integer;
    a, b, x, x1: extended;

procedure check;
begin
  if x > x1 then
    right := k
  else
    left := k;
end;

begin
    readln(n);
    left := 0;
    right := n + 1;
    while ((left + 1) < right) do begin
        k := (left + right) div 2;
        a := trunc(k * ((k + 1)/2));
        b := trunc(n * ((n + 1)/2)) - a;
        x := abs(a - b);
        x1 := abs((a - k) - (b + k));
        check;
    end;
    writeln(left);
end.