program lab23;

var
  n, s, t: int64;
  i, j: integer;

begin
  read(n);

  for i := 1 to n do
  begin
    t := 1;
    for j := 1 to i do
      t := t * i;

    s := s + t;
  end;

  writeln(s);
  readln;
  readln;
end.