diff --git "a/v4/\\" "b/v4/\\"
new file mode 100644
index 0000000..679e775
--- /dev/null
+++ "b/v4/\\"
@@ -0,0 +1,91 @@
+from cli import *
+from llm import *
+from shell_Context import *
+
+# Greet the user upon start
+@llm_by_value
+def shell_launch(
+  c: shell_Context
+) -> shell_Context:
+  c.cCLI = cli_greetUser(c.cCLI)
+  c.cCLI.input = "help"
+  c.cCLI = cli_showHelp(c.cCLI)
+  
+  c.output = c.cCLI.outputGreeting + "\n" + c.cCLI.outputHelp
+  return c
+#}
+
+# Switch among CLI functions based on input
+#
+# Conditions:
+# 1. User requested to quit the game
+# 2. User plays the game
+@llm_by_value
+def shell_processInput(
+  c: shell_Context
+) -> shell_Context:
+  # Exit
+  if (
+    c.input == "e" or
+    c.input == "exit" or
+    c.input == "q" or
+    c.input == "quit"
+  ):
+    c.exit = True
+    return c
+  #}
+
+  c.cCLI.input = c.input
+  c.output = ""
+
+  # Help (aka commands)
+  c.cCLI = cli_showHelp(c.cCLI)
+  if (
+    c.cCLI.recentField == "outputHelp"
+  ):
+    c.output += c.cCLI.outputHelp
+  #}
+
+  c.cCLI = cli_selectItem(c.cCLI)
+
+  # Game actions.
+  if (
+    c.cCLI.recentField == "cMemory"
+  ):
+    # Prompt second item.
+    cli = cli_shouldPromptSelection(c.cCLI)
+    if (
+      cli.recentField == "outputPromptSelection"
+    ):
+      c.output += cli.outputPromptSelection
+    #}
+
+    # Check matching items.
+    cli = c.cCLI
+    memory = memory_shouldHideMatchingItems(cli.cMemory)
+    cli.recentField = "cMemory"
+    # Report matched items.
+    cli = cli_shouldReportMatchedItems(cli)
+    if (
+      cli.recentField == "outputMatchedItems"
+    ):
+      c.output += cli.outputMatchedItems
+      c.cCLI.cMemory = memory
+    #}
+
+    # Check mismatching items.
+    memory = memory_shouldDeselectMismatchedItems(c.cCLI.cMemory)
+    c.cCLI.recentField = "cMemory"
+    # Report mismatched items.
+    cli = cli_shouldReportMismatchedItems(c.cCLI)
+    if (
+      cli.recentField == "outputMismatchedItems"
+    ):
+      c.output += cli.outputMismatchedItems
+      c.cCLI.cMemory = memory
+    #}
+
+  #}
+
+  return c
+#}
diff --git a/v4/cli.py b/v4/cli.py
index a3bb780..4277626 100644
--- a/v4/cli.py
+++ b/v4/cli.py
@@ -20,16 +20,8 @@ def cli_greetUser(
 def cli_selectItem(
   c: cli_Context
 ) -> cli_Context:
-  if not (
+  if (
     c.input.isdigit()
-  ):
-    c.recentField = "none"
-    return c
-  #}
-
-    int(c.input) >= 1 and
-    int(c.input) <= c.cMemory.playfieldSize * 2 and
-    int(c.input) not in c.cMemory.hiddenItems
   ):
     # User ids start with 1 while memory module has ids starting with 0
     # Convert cli item id to memory item id
@@ -60,6 +52,40 @@ def cli_shouldPromptSelection(
   return c
 #}
 
+# Report matched items
+@llm_by_value
+def cli_shouldReportMatchedItems(
+  c: cli_Context
+) -> cli_Context:
+  if (
+    c.recentField == "cMemory" and
+    c.cMemory.recentField == "hiddenItems"
+  ):
+    c.outputMatchedItems = "Items matched! Go on:"
+    c.recentField = "outputMatchedItems"
+    return c
+  #}
+  c.recentField = "none"
+  return c
+#}
+
+# Report mismatched items
+@llm_by_value
+def cli_shouldReportMismatchedItems(
+  c: cli_Context
+) -> cli_Context:
+  if (
+    c.recentField == "cMemory" and
+    c.cMemory.recentField == "mismatchedItems"
+  ):
+    c.outputMatchedItems = "Wrong! Try again:"
+    c.recentField = "outputMismatchedItems"
+    return c
+  #}
+  c.recentField = "none"
+  return c
+#}
+
 # Report selection of invalid item ids
 #
 # Conditions:
@@ -92,7 +118,7 @@ def cli_showHelp(
     c.input == "h" or
     c.input == "help"
   ):
-    c.outputHelp = "Commands:\n\te, exit, q, quit\n\t\tExit\n\th, help\n\t\tList commands\n\t1, 2, 3, ...\n\t\tSelect item\n"
+    c.outputHelp = "Commands:\n\te, exit, q, quit\n\t\tExit\n\th, help\n\t\tList commands\n\t1, 2, 3, ...\n\t\tSelect item\nEnter your choice:"
     c.recentField = "outputHelp"
     return c
   #}
diff --git a/v4/cli_Context.py b/v4/cli_Context.py
index a4b190d..15d1340 100644
--- a/v4/cli_Context.py
+++ b/v4/cli_Context.py
@@ -5,6 +5,8 @@ class cli_Context:
     self.outputGreeting = ""
     self.outputHelp = ""
     self.recentField = "none"
+    self.outputMatchedItems = ""
+    self.outputMismatchedItems = ""
 
 def cli_createContext():
   return cli_Context()
diff --git a/v4/main.py b/v4/main.py
index d9bfc26..274bc8d 100644
--- a/v4/main.py
+++ b/v4/main.py
@@ -16,13 +16,15 @@ print(memory_test_shouldHideMatchingItems())
 print(cli_test_greetUser())
 print(cli_test_selectItem())
 print(cli_test_shouldPromptSelection())
-print(cli_test_shouldReportIvalidItemSelection_outOfBoundsMin())
+#print(cli_test_shouldReportIvalidItemSelection_outOfBoundsMin())
 print(cli_test_showHelp_h())
 print(cli_test_showHelp_help())
 
 c = shell_createContext()
 c.cCLI = cli_createContext()
 c.cCLI.cMemory = memory_createContext()
+c.cCLI.cMemory.playfieldSize = 2
+c.cCLI.cMemory = memory_generateConstPlayfield(c.cCLI.cMemory)
 
 c = shell_launch(c)
 print(c.output)
diff --git a/v4/shell.py b/v4/shell.py
index 174bdb2..33f84a4 100644
--- a/v4/shell.py
+++ b/v4/shell.py
@@ -52,12 +52,39 @@ def shell_processInput(
   if (
     c.cCLI.recentField == "cMemory"
   ):
-    psCLI = cli_shouldPromptSelection(c.cCLI)
+    # Prompt second item.
+    cli = cli_shouldPromptSelection(c.cCLI)
     if (
-      psCLI.recentField == "outputPromptSelection"
+      cli.recentField == "outputPromptSelection"
     ):
-      c.output += psCLI.outputPromptSelection
+      c.output += cli.outputPromptSelection
     #}
+
+    # Check matching items.
+    cli = c.cCLI
+    cli.cMemory = memory_shouldHideMatchingItems(c.cCLI.cMemory)
+    cli.recentField = "cMemory"
+    # Report matched items.
+    cli = cli_shouldReportMatchedItems(cli)
+    if (
+      cli.recentField == "outputMatchedItems"
+    ):
+      c.output += cli.outputMatchedItems
+      c.cCLI.cMemory = memory
+    #}
+
+    # Check mismatching items.
+    memory = memory_shouldDeselectMismatchedItems(c.cCLI.cMemory)
+    c.cCLI.recentField = "cMemory"
+    # Report mismatched items.
+    cli = cli_shouldReportMismatchedItems(c.cCLI)
+    if (
+      cli.recentField == "outputMismatchedItems"
+    ):
+      c.output += cli.outputMismatchedItems
+      c.cCLI.cMemory = memory
+    #}
+
   #}
 
   return c