Remove .md and image files and move python files into main chapter folders

thinkcspy/Chapter-9-Exercises/Problem19.py

@@ -0,0 +1,24 @@
+# Runestone.Academy thinkcspy course
+# Chapter 9
+# Problem 19
+
+import string
+
+def decrypt(msg, code):
+    alpha = string.ascii_lowercase
+    newStr = ""
+    pos = 0
+    msg = msg.lower()
+    
+    for char in msg:
+        if char in alpha:
+            pos = newAlpha.index(char)
+            newStr += alpha[pos]
+        else:
+            newStr += char    # no rules apply so keep the character
+
+    return newStr
+
+newAlpha = "qwertyuiopasdfghjklzxcvbnm"
+
+print(decrypt("itssg vgksr!", newAlpha))