var
 i,s,n,k,d:longint;
 f,g:text;
begin
 assign(f,'cifra.in');
 reset(f);
 read(f,n);
 close(f);
 k:=1;
 s:=0;
 repeat
  d:=1;
  for I:=1 to k do
   d:=d*k;
  s:=s+d;
  k:=k+1;
 until (k>n);
 assign(g,'cifra.out');
 rewrite(g);
 write(g,s mod 10);
 close(g);
 write(s);
end.