var a,b:qword;
    i,j,m,n:longint;
    s:string;
begin
assign(input,'cifra.in');
reset(input);
readln(s);
close(input);
if  length(s)>2 then s:=s[length(s)-1]+s[length(s)];
val(s,n,m);
assign(output,'cifra.out');
rewrite(output);
{for n:=1 to 150 do
begin
a:=0;}
 for i:=1 to n do
  begin
   b:=1;
   for j:=1 to i do
    begin  b:=b*i; b:=b mod 1000; end;

   a:=a+b;
   a:=a mod 10;
  end;
writeln(a mod 10);
{end;}

close(output);
end.