diff --git a/ch05_modules/ls.py b/ch05_modules/ls.py
index 842c4c4..bbc8eca 100755
--- a/ch05_modules/ls.py
+++ b/ch05_modules/ls.py
@@ -1,51 +1,149 @@
 #!/usr/bin/env python3
+import locale
 import os
-from pprint import pprint
+from datetime import datetime
+from optparse import OptionParser
+
+FULL_PATH, IS_FILE, FILE_SIZE, FILE_MTIME = range(4)
 
 
 def is_hidden_path(path):
     return path.startswith(".")
 
 
-def main():
-    # TODO: sanitize input roots - expanduser, expandvars, abspath
-    roots = ["/home/mkiryanov/", ".local/"]
+def by_path_name(stat_item):
+    return stat_item[FULL_PATH]
+
+
+def by_file_size(stat_item):
+    size = stat_item[FILE_SIZE]
+    return size if size else 0
+
+
+def by_file_mtime(stat_item):
+    mtime = stat_item[FILE_MTIME]
+    return mtime if mtime else 0
+
 
-    recursive = True
-    show_hidden = False
+def gather_fs_stats_simply(root, show_hidden):
+    stats = []
+    for filename in os.listdir(root):
+        if not show_hidden and is_hidden_path(filename):
+            continue
+        full_path = os.path.join(root, filename)
+        if not os.path.isdir(full_path):
+            stat = os.stat(full_path, follow_symlinks=False)
+            data = (full_path, True, stat.st_size, stat.st_mtime)
+        else:
+            data = (full_path, False, None, None)
+        stats.append(data)
+    return stats
 
-    stats = {}
+
+def gather_fs_stats_recursively(root_name, show_hidden):
+    stats = []
+    for root, dirnames, filenames in os.walk(root_name):
+        for path in dirnames:
+            if not show_hidden and is_hidden_path(path):
+                continue
+            full_path = os.path.join(root, path)
+            stats.append((full_path, False, None, None))
+        for path in filenames:
+            if not show_hidden and is_hidden_path(path):
+                continue
+            full_path = os.path.join(root, path)
+            stat = os.stat(full_path, follow_symlinks=False)
+            stats.append((full_path, True, stat.st_size, stat.st_mtime))
+
+        dirnames[:] = [dir for dir in dirnames if not is_hidden_path(dir)]
+    return stats
+
+
+def gather_fs_stats(root_names, recursive, show_hidden):
+    stats = []
     if not recursive:
-        for root in roots:
-            abs_root = os.path.abspath(root)
-            for path in os.listdir(root):
-                if not show_hidden and is_hidden_path(path):
-                    continue
-                abs_path = os.path.join(abs_root, path)
-                data = None
-                if not os.path.isdir(abs_path):
-                    stat = os.stat(abs_path)
-                    rel_path = os.path.join(root, path)
-                    data = (rel_path, stat.st_size, stat.st_mtime_ns)
-                stats.update({abs_path: data})
+        for root_name in root_names:
+            stats.extend(gather_fs_stats_simply(root_name, show_hidden))
+    else:
+        for root_name in root_names:
+            stats.extend(gather_fs_stats_recursively(root_name, show_hidden))
+    return stats
+
+
+def print_stats(stats, show_size, show_time, locale_id):
+    locale.setlocale(locale.LC_ALL, locale_id)
+
+    print_template = "{name:<s}"
+    if show_size:
+        print_template = "{size: >15{size_fmt}} " + print_template
+    if show_time:
+        print_template = "{time: <20} " + print_template
+
+    file_count = 0
+    dir_count = 0
+
+    for stat in stats:
+        name = stat[FULL_PATH]
+        if stat[IS_FILE]:
+            file_count += 1
+
+            if show_size:
+                size = stat[FILE_SIZE]
+                size_fmt = "n"
+            if show_time:
+                time = datetime.utcfromtimestamp(stat[FILE_MTIME]).strftime("%x %X")
+        else:
+            dir_count += 1
+
+            if show_size:
+                size = ""
+                size_fmt = ""
+            if show_time:
+                time = ""
+
+        print(print_template.format(**locals()))
+    print("\n{0} file{1}, {2} director{3}".format(file_count, "" if file_count == 1 else "s",
+                                                  dir_count, "y" if dir_count == 1 else "ies"))
+
+
+def resolve_order_func(order_option):
+    if order_option in ("name", "n"):
+        return by_path_name
+    elif order_option in ("modified", "m"):
+        return by_file_mtime
     else:
-        for root in roots:
-            for root, dirnames, filenames in os.walk(root):
-                abs_root = os.path.abspath(root)
-                for path in dirnames:
-                    if not show_hidden and is_hidden_path(path):
-                        continue
-                    stats.update({os.path.join(abs_root, path): None})
-                for path in filenames:
-                    if not show_hidden and is_hidden_path(path):
-                        continue
-                    abs_path = os.path.join(abs_root, path)
-                    stat = os.stat(abs_path, follow_symlinks=False)
-                    rel_path = os.path.join(root, path)
-                    data = (rel_path, stat.st_size, stat.st_mtime_ns)
-                    stats.update({abs_path: data})
-
-    pprint(stats.values())
+        return by_file_size
+
+
+def process_options():
+    usage = ("%prog [options] [path1 [path2 [... pathN]]]\n"
+             "The paths are optional; if not given . is used.")
+    parser = OptionParser(usage=usage)
+    parser.add_option("-H", "--hidden",
+                      action="store_true", dest="show_hidden", default=False,
+                      help="show hidden files [default: off]")
+    parser.add_option("-m", "--modified",
+                      action="store_true", dest="show_time", default=False,
+                      help="show last modified date/time [default: off]")
+    parser.add_option("-o", "--order",
+                      type="choice", choices=["name", "n", "modified", "m", "size", "s"], default="name",
+                      help="order by ('name', 'n', 'modified', 'm', 'size', 's') [default: name]")
+    parser.add_option("-r", "--recursive",
+                      action="store_true", dest="recursive", default=False,
+                      help="recurse into subdirectories [default: off]")
+    parser.add_option("-s", "--sizes",
+                      action="store_true", dest="show_size", default=False,
+                      help="show sizes [default: off]")
+    return parser.parse_args()
+
+
+def main():
+    (options, args) = process_options()
+
+    root_names = args if args else "."
+    stats = gather_fs_stats(root_names, options.recursive, options.show_hidden)
+    print_stats(sorted(stats, key=resolve_order_func(options.order)),
+                options.show_size, options.show_time, "ru_RU.UTF-8")
 
 
 main()