program ucif;

var i, n, us, up, j: integer;
    fin, fout: Text;

begin
  assign(fin, 'ucif.in'); Reset(fin);
  readln(fin, n);
  close(fin);

  us:=0;
  for i:=1 to n do
    begin
      up:=1;
      for j:=1 to i do
        up:= up*i mod 10;
      us:=(us+up) mod 10;
    end;

  assign(fout, 'ucif.out'); rewrite(fout);
  writeln(fout, us);
  close(fout);
end.