program kk;
var f,g:text;
    n,m,inv,nr,uc:longint;
begin
assign(f,'cifra1.in');
reset(f);
assign(g,'cifra1.out');
rewrite(g);
read(f,n,m);
inv:=0;
  while n>0 do
    begin
     inv:=inv*10+n mod 10;
      n:=n div 10;
    end;
    while inv>0 do
      begin
      uc:=inv mod 10;
      nr:=nr+uc;
        if m<=nr then
          begin
          writeln(g,uc);
          break;
          end;
        inv:=inv  div 10;
      end;
close(f);
close(g);
end.