diff --git a/.gitignore b/.gitignore
index 99010fe..2dec1e4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -4,3 +4,4 @@ __pycache__
 .idea
 result*.json
 groups.json
+diffable_dates.txt
\ No newline at end of file
diff --git a/links_parser.py b/links_parser.py
index 3553032..584a02f 100644
--- a/links_parser.py
+++ b/links_parser.py
@@ -10,6 +10,11 @@ from bs4 import BeautifulSoup
 BASE_URL = "https://www.vstu.ru/"
 RASP_PREFIX = "https://www.vstu.ru/student/raspisaniya/zanyatiy/index.php?dep="
 
+def sibling_clear_to_date(s: str):
+    if s is None:
+        return "!!!Python None!!!"
+    return s.lower().replace("(последнее изменение:", "").replace(")", "").strip()
+
 # Парсит ссылки на эксель .xls & .xlsx файлы и выдаёт их
 def parse_links(facultets):
     session = requests.Session()
@@ -27,7 +32,7 @@ def parse_links(facultets):
         }
     )
 
-    EXCEL_LINKS = {}
+    EXCEL_LINKS = []
     for facultet in facultets:
         url = RASP_PREFIX + facultet
         print("getting...")
@@ -38,19 +43,23 @@ def parse_links(facultets):
 
         # Ищем все теги <a>, у которых атрибут href соответствует нашему паттерну
         excel_tags = soup.find_all('a', href=excel_pattern)
-        excel_links = [tag.get('href') for tag in excel_tags]
-
-        # Предположим, вы уже получили excel_links из одного из методов выше
-        # excel_links = ['../../../upload/raspisanie/z/ОН_ХТФ_1 курс.xlsx', ...]
-
-        absolute_links = [urljoin(BASE_URL, relative_link) for relative_link in excel_links]
-
-        if facultet not in EXCEL_LINKS.keys():
-            EXCEL_LINKS[facultet] = set()
-
-        for excel_url in absolute_links:
-            EXCEL_LINKS[facultet].add(excel_url)
-            print(f"+url {excel_url}")
+        for a in excel_tags:
+            last_changed = sibling_clear_to_date(a.next_sibling)
+            url = urljoin(BASE_URL, a.get('href'))
+            record = {
+                "facultet": facultet,
+                "url": url,
+                "last_changed": last_changed
+            }
+            print(record)
+            EXCEL_LINKS.append(record)
     
-    return EXCEL_LINKS
+    return sorted(EXCEL_LINKS, key=lambda x: x['url'])
 
+
+def excels_to_diffabledates(excels):
+    dates = []
+    for excel in excels:
+        dates.append(f"{excel['last_changed']} {excel['facultet']} {excel['url']}")
+    
+    return "\n".join(sorted(dates)).strip()
diff --git a/main.py b/main.py
index f78a644..4f6fa2c 100644
--- a/main.py
+++ b/main.py
@@ -19,10 +19,11 @@ import shutil
 def currt():
     return round(time.time())
 
-FACULTETS = [
+FACULTETS = sorted([
     "asp", "mag", "fastiv", "fat", "ftkm", "ftpp", "feu", "fevt", "htf", "vkf", "mmf", "fpik"
-]
+])
 DIRNAME = "excels"
+DIFFABLE_DATES = "diffable_dates.txt"
 
 DEBUG_ONE_FAC = None #'htf'
 result_groups = {}
@@ -63,20 +64,15 @@ result = {
     "see_header_at_top_of_this_file": "SEE TOP OF THIS FILE | ОБРАТИТЕ ВНИМАНИЕ НА ВЕРХ ЭТОГО ФАЙЛА"
 }
 
-def process_excel_file(facultet, excel_url, counter, timeid):
+def process_excel_file(facultet, excel_url, counter, latest_changed):
     is_xlsx = excel_url.endswith(".xlsx")
-    filename = f"{DIRNAME}/" + timeid + f"_[C{counter}]_" + facultet + ".xls" + ("x" if is_xlsx else "")
+    filename = f"{DIRNAME}/" + f"_[C{counter}]_" + facultet + ".xls" + ("x" if is_xlsx else "")
 
     excel_info = {
         "filename": excel_url.split("/")[-1],
         "url": excel_url,
+        "latest_changed": latest_changed,
         "download_place": filename,
-        "stat": {
-            "download": -1,
-            "create_reader": -1,
-            "parse": -1,
-            "cycles": 0
-        },
         "group_names_parsed": [],
         "facultet": facultet,
         "counter": counter
@@ -84,17 +80,12 @@ def process_excel_file(facultet, excel_url, counter, timeid):
     parser.LOGGING = False
 
     try:
-        t = utils.StepTimeCounter()
         aigenerated.download_file_from_url(excel_url, filename)
-        excel_info["stat"]['download'] = t.step()
-
         reader = translations.create_reader(filename)
         print("Reader info")
         print(reader.info())
-        excel_info["stat"]['create_reader'] = t.step()
-
+        
         while True:
-            excel_info['stat']['cycles'] += 1
             print(f"Parsing sheet №{reader.get_sheet_index()+1} (from 1)")
             prs = parser.Parser(reader)
 
@@ -103,7 +94,7 @@ def process_excel_file(facultet, excel_url, counter, timeid):
 
             print("parsed done!")
             if prs.parser_error is not None:
-                excel_info["parser_error_cycle_" + str(excel_info['stat']['cycles'])] = prs.parser_error
+                excel_info["parser_error_cycle_" + str(reader.get_sheet_index()+1)] = prs.parser_error
 
             for group_name in prs.groups.keys():
                 if group_name in result_groups.keys():
@@ -121,8 +112,6 @@ def process_excel_file(facultet, excel_url, counter, timeid):
                 gr['facultet'] = facultet
                 gr['data_source'] = excel_url.split("/")[-1]
                 gr['debug'] = {
-                    "counter": counter,
-                    "timeid": timeid,
                     "excel_url": excel_url,
                     "reader_info": reader.info(),
                     "reader_sheet_index": reader.get_sheet_index(),
@@ -138,9 +127,6 @@ def process_excel_file(facultet, excel_url, counter, timeid):
             else:
                 reader.next_sheet()
                 print("Next sheet!")
-
-        excel_info["stat"]['parse'] = t.step()
-
         
     except Exception as e:
         print(f"Error while {excel_url}")
@@ -164,6 +150,7 @@ def process_excel_file(facultet, excel_url, counter, timeid):
 
 faileds = []
 def main():
+    global result_groups, result
     t = utils.StepTimeCounter()
     try:
         try:
@@ -179,22 +166,34 @@ def main():
 
     print("main(); parse links starting...")
     EXCEL_LINKS = links_parser.parse_links(FACULTETS if DEBUG_ONE_FAC is None else [DEBUG_ONE_FAC])
-    counter = 0
-    timeid = str(round(time.time()))
-    for facultet in EXCEL_LINKS.keys():
-        counter += 1000
-        print(f"\n\n-- Факультет '{facultet}' --")
-        facultet_urls = EXCEL_LINKS[facultet]
-        for excel_url in facultet_urls:
-            counter += 1
-            print(f"\n\n-- Ссылка --")
-            print(f"{excel_url}")
-            
-            print("Start processing excel file")
-            process_excel_file(facultet, excel_url, counter, timeid)
-            print("Excel file processing done!")
+    now_diffable_dates = links_parser.excels_to_diffabledates(EXCEL_LINKS)
+    prev_diffable_dates = None
+    if os.path.exists("diffable_dates.txt"):
+        with open(DIFFABLE_DATES, 'r') as fp:
+            prev_diffable_dates = fp.read().strip()
+    
+    with open(DIFFABLE_DATES, 'w') as fp:
+        fp.write(now_diffable_dates)
+
+    if now_diffable_dates == prev_diffable_dates:
+        print("No date changes in vstu.ru website. Stopping")
+        return
+    
+    counter = 10000
+    for excel_link in EXCEL_LINKS:
+        counter += 1
+        facultet = excel_link['facultet']
+        excel_url = excel_link['url']
+        latest_changed = excel_link['last_changed']
+        process_excel_file(facultet, excel_url, counter, latest_changed)
 
     print("Saving result.json")
+    group_names_alphabeticaly = sorted(result_groups.keys())
+    sorted_groups = {}
+    for group_name in group_names_alphabeticaly:
+        sorted_groups[group_name] = result_groups[group_name]
+
+    result['groups'] = sorted_groups
 
     result['stat']['total_parsing_time'] = t.step()