program Program3; var m, n :

program Program3;
var
  m, n : integer;
  mark : Boolean;
function test(m, N : integer) : integer;
var
  i, p : integer;
  flag : boolean;
begin
  m := m - 1;
  i := 0;
  flag := False;
  for p:= 2 * N downto (N + 1) do
  begin
    i := (i + m) mod p;
    if (i
    begin
    test := 0;
    flag := Ture;
    Break;
  end
end;
if not(flag) then     test:=1;
end;
begin
  read(n);
  m := 1;
  Mark := False;
  repeat
    if (test(m, n) = 1) then
    begin
      writeln(m);
      break;
    end;
    m := m + 1;
  until Mrak;
end.