renamed files and exercise 1.2

Activity_3_python/exercises_3/exercise_3_6_2.py

@@ -0,0 +1,16 @@
+msg = input("Message à coder ? ")
+res = ""
+alph = 'abcdefghijklmnopqrstuvwxyz'
+
+for i in msg:
+    if i == ' ' or i =="'":
+        res += i
+        
+    else:
+        p = alph.find(i)
+        t = p - 3
+        if t < 0:
+            t = 26 + t
+        res += alph[t]
+
+print(res)