Add exercises 1, 2 and 3

Activity_3_python/exercise_2/ex2_3.py

@@ -0,0 +1,12 @@
+note = int(input("Note au bac (sur 20) : "))
+
+if note < 10:
+    print("recalé")
+elif note < 12:
+    print("Pas de mention")
+elif note < 14:
+    print("Assez bien")
+elif note < 16:
+    print("Bien")
+else:
+    print("Félissitation")