program ultimaCifra;

var
  pc:byte;
  uc:byte;
  rez:byte;
  f,o:text;
  i,T:integer;

function fx(n:integer):integer;
begin
  case n of
   0: fx:=0;
   1: fx:=1;
   2: fx:=5 + (((pc mod 2) * 2) mod 2) * 2;
   3: fx:=2;
   4: fx:=8;
   5: fx:=3;
   6: fx:=9;
   7: fx:=2;
   8: fx:=0;
   9: fx:=9;
  end;
end;

begin
  assign(f,'cifra.in');
  reset(f);
  assign(o,'cifra.out');
  rewrite(o);

  read(f,T);
  for i:=1 to T do begin
        readln(f);
	pc:=0;
	read(f,uc);
	while not(eoln(f)) do
	begin
	  pc := uc;
	  read(f,uc);
	end;
	rez:=(3 * pc + (pc mod 2) * 2 + fx(uc)) mod 10;
	writeln(o, rez);
  end;
  close(f);
  close(o);
end.