#!/usr/bin/env python3

import re
import markdown2

# https://stackoverflow.com/a/6041965
RE_URL = re.compile(
    r"(https?://([\w_-]+(?:(?:\.[\w_-]+)+))([\w.,@?^=%&:/~+#-]*[\w@?^=%&/~+#-]))"
)
RE_EM = re.compile(r"\*(.*?)\*")
RE_LIST = re.compile(r"(-|[0-9]\.) .*")

RE_PLAINURL = re.compile(
    r"(?P<pre>^|\s|\n)(?P<url>https?://([\w_-]+(?:(?:\.[\w_-]+)+))([\w.,@?^=%&:/~+#-]*[\w@?^=%&/~+#-]))(?P<post>\s|\n|$)"
)

def html(text):
    text = RE_PLAINURL.sub(r'\g<pre>[\g<url>](\g<url>)\g<post>', text)
    return markdown2.markdown(text)


def html_old(text):
    # Replace angle brackets to prevent XSS
    # Also replace ampersands to prevent surprises.
    text = text.replace("&", "&amp;").replace("<", "&lt;").replace(">", "&gt;")

    html = ["<p>"]
    lines = text.split("\n")
    in_code = False
    in_list = False

    for l in lines:
        if l == "":
            in_list = False
            if in_code:
                html.append("</pre>")
                in_code = False
            html.append("</p><p>")
            continue
        if l.startswith("  "):
            in_list = False
            l = l[2:]
            if not in_code:
                html.append("<pre>")
                in_code = True
            html.append(l)
            continue
        if in_code:
            html.append("</pre>")
            in_code = False
        l = RE_EM.sub(r"<em>\1</em>", l)
        l = RE_URL.sub(r'<a href="\1">\1</a>', l)
        if RE_LIST.match(l):
            if in_list:
                html.append("<br>")
            in_list = True
        else:
            in_list = False
        html.append(l)

    if in_code:
        html.append("</pre>")
    html.append("</p>")
    return "\n".join(html)


if __name__ == "__main__":
    import sys

    print(html_old(sys.stdin.read()))