Program cifra;
 var f,g:text; t,a,i,r,s:integer;
     b:char; c:string; code:word;
 begin
  assign (f,'cifra.in'); reset (f);
  assign (g,'cifra.out'); rewrite (g);
  readln (f,t);
  for i:=1 to t do begin
    c:='00';
    while not eoln (f) do begin
      read (f,b);
      c:=c[2]+b;
    end;
    readln (f);
    val (c,r,code);
    s:=4*(r div 20);
    case r mod 20 of
      1,17: s:=s+1;
      3,7: s:=s+2;
      5,14: s:=s+3;
      12,19: s:=s+4;
      2,18: s:=s+5;
      9,10,13: s:=s+7;
      4,8,11,15: s:=s+8;
      6: s:=s+9;
    end;
    writeln (g,s mod 10);
  end;
  close (f); close (g);
 end.