program cifra;
var i,p,s,x,cif,j:longint; f,g:text;
begin
assign(f,'cifra.in');
reset(f);
assign(g,'cifra.out');
rewrite(g);
readln(f,x);
while not eof(f) do
 begin
  readln(f,x);
  p:=1;
  s:=0;
  for i:=1 to x do
  begin
  p:=1;
  for j:=1 to i do
   p:=p*i;
  s:=s+p;
  end;
  cif:=s mod 10;
 writeln(g,cif);
end;
close(f);
close(g);
end.