add exit function

 def echo():
-    i = input("입력해주세요: ")
-    print(i)
+    user = input("입력해주세요: ")
+    print(user)
+    
 
-echo()
+#echo()
     
+def exit():
+    user = input("입력해주세요: ")
+    if user == "exit":
+        return;
+
+    else:
+        print(user)
+
+exit()