diff --git a/file_input.txt b/file_input.txt
index ca8c2a8..3cbad6d 100644
--- a/file_input.txt
+++ b/file_input.txt
@@ -1,5 +1,7 @@
+# some comment
 "0261","+","Apple iPhone XR 128GB Red","https://www.apple.com/shop/buy-iphone/iphone-xr/6.1-inch-display-128gb-red-unlocked","12.5"
 "0092","+","Samsung Galaxy S21 5G 128GB Phantom Gray","https://www.samsung.com/us/smartphones/galaxy-s21-5g/buy/galaxy-s21-5g-128gb-unlocked-sm-g991uzkaxaa/","11.0"
+# another comment
 "0035","+","Sony WH-1000XM4 Wireless Noise Cancelling Headphones","https://www.amazon.com/Sony-WH-1000XM4-Canceling-Headphones-Phone-Call/dp/B08CVRNPRZ/","4.3.0.0"
 "0054","+","Bose QuietComfort 35 II Wireless Bluetooth Headphones","https://www.amazon.com/Bose-QuietComfort-Wireless-Headphones-Cancelling/dp/B0756CYWWD/","4.5.2.0"
 "0169","+","Apple iPad Pro 11-inch Wi-Fi 256GB - Space Gray","https://www.apple.com/shop/buy-ipad/ipad-pro/11-inch-display-256gb-space-gray-wifi","14.5"
diff --git a/file_output.txt b/file_output.txt
index fe4b906..6b809a6 100644
--- a/file_output.txt
+++ b/file_output.txt
@@ -1,5 +1,7 @@
+# some comment
 "0001","+","Apple iPhone XR 128GB Red","https://www.apple.com/shop/buy-iphone/iphone-xr/6.1-inch-display-128gb-red-unlocked","12.5"
 "0002","+","Samsung Galaxy S21 5G 128GB Phantom Gray","https://www.samsung.com/us/smartphones/galaxy-s21-5g/buy/galaxy-s21-5g-128gb-unlocked-sm-g991uzkaxaa/","11.0"
+# another comment
 "0003","+","Sony WH-1000XM4 Wireless Noise Cancelling Headphones","https://www.amazon.com/Sony-WH-1000XM4-Canceling-Headphones-Phone-Call/dp/B08CVRNPRZ/","4.3.0.0"
 "0004","+","Bose QuietComfort 35 II Wireless Bluetooth Headphones","https://www.amazon.com/Bose-QuietComfort-Wireless-Headphones-Cancelling/dp/B0756CYWWD/","4.5.2.0"
-"0005","+","Apple iPad Pro 11-inch Wi-Fi 256GB - Space Gray","https://www.apple.com/shop/buy-ipad/ipad-pro/11-inch-display-256gb-space-gray-wifi","14.5"
\ No newline at end of file
+"0005","+","Apple iPad Pro 11-inch Wi-Fi 256GB - Space Gray","https://www.apple.com/shop/buy-ipad/ipad-pro/11-inch-display-256gb-space-gray-wifi","14.5"
diff --git a/main.py b/main.py
index 4ae49fc..55c6ba4 100644
--- a/main.py
+++ b/main.py
@@ -1,16 +1,53 @@
 # define custom opening and closing brackets for id
 id_opening_bracket = "\""
 id_closing_bracket = "\""
+# define custom lines separator
 lines_separator = ","
+# initialize line counter
+i = 0
+# initialize output lines list
+output_lines = []  
 
+
+##############################
+#                            #
+#    open your input file    #
+#                            #
+##############################
 with open('file_input.txt', 'r') as f:
     lines = f.readlines()
 
-for i, line in enumerate(lines):
-    line = line.strip().split(lines_separator)  # split line by comma
-    line[0] = id_opening_bracket + f"{i+1:04}" + id_closing_bracket  # re-enumerate the first value
-    line = lines_separator.join(line)  # join the modified values with comma
-    lines[i] = line
 
+#################################
+#                               #
+#    parse lines - main loop    #
+#                               #
+#################################
+for line in lines:
+    # process comments
+    if line.startswith("#"):
+        # add comment to output lines 
+        # "rstrip()" removes the line break character (writes your comment without extra line break after it)
+        output_lines.append(line.rstrip())
+    # process non-comment lines
+    else:
+        # split line by comma
+        line = line.strip().split(lines_separator)
+        # re-enumerate the first value
+        line[0] = id_opening_bracket + f"{i+1:04}" + id_closing_bracket
+        # join the modified values with comma
+        line = lines_separator.join(line)
+        # add modified line to output lines
+        output_lines.append(line)
+        i += 1
+
+
+########################################
+#                                      #
+#    write data to your output file    #
+#                                      #
+########################################
 with open('file_output.txt', 'w') as f:
-    f.write('\n'.join(lines))
\ No newline at end of file
+    # add line break at the end of the file
+    f.write('\n'.join(output_lines) + '\n')
+    
\ No newline at end of file