Update Day6.md

I've added a short  solution, using Regular Expression,  to the Question 18.

Author: pratikb0501

Status/Day 6.md

@@ -153,6 +153,18 @@ for i in s:
 print(",".join(lst))
 ```
 
+**OR**
+
+'''python
+import re
+
+a = input('Enter passwords: ').split(',')
+pass_pattern = re.compile(r"^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[$#@]).{6,12}$")
+for i in a:
+    if pass_pattern.fullmatch(i):
+        print(i)
+'''
+
 ---
 
 # Question 19