!752

answer {

  if "how many elements are in the list *" {

    L list = cast safeUnstructure(m.unq(0));

    ret str(l(list));

  }

  if "what is the * element in the list *" {

    S x = m.unq(0).toLowerCase();

    L list = cast safeUnstructure(m.unq(1));

    if (eq(x, "first"))

      ret structure(first(list));

    if (eq(x, "last"))

      ret structure(last(list));

    // "1st", "2nd" etc  

    int i = 0;

    while (i < l(x) && isDigit(x.charAt(i)))

      ++i;

    if (i > 0)

      ret structure(get(list, parseInt(x.substring(0, i))-1));

  }

  // It should match if you write: "what is the 1st element..."

  // cause the tokenizer works like that...

  if (match("what is the * st element in the list *", s, m)

    || match("what is the * nd element in the list *", s, m)

    || match("what is the * rd element in the list *", s, m)

    || match("what is the * th element in the list *", s, m)) {

    L list = cast safeUnstructure(m.unq(1));

    ret structure(get(list, parseInt(m.unq(0))-1));

  }

}