diff --git a/4-grow-only-counter/src/main.rs b/4-grow-only-counter/src/main.rs
index 6b9490a..9a3e2b3 100644
--- a/4-grow-only-counter/src/main.rs
+++ b/4-grow-only-counter/src/main.rs
@@ -13,6 +13,11 @@ struct Message {
 #[serde(tag = "type")]
 #[serde(rename_all = "snake_case")]
 enum Body {
+	Error {
+		in_reply_to: u64,
+		code: u64,
+		text: String,
+	},
 	Init {
 		msg_id: u64,
 		node_id: String,
@@ -21,21 +26,27 @@ enum Body {
 	InitOk {
 		in_reply_to: u64,
 	},
-	Add {
-		delta: u64,
-		msg_id: u64,
-		in_reply_to: u64,
-	},
-	AddOk {
-		msg_id: u64,
-		in_reply_to: u64,
-	},
 	Read {
 		msg_id: u64,
 	},
 	ReadOk {
 		value: u64,
+		in_reply_to: u64,
+	},
+	Add {
 		msg_id: u64,
+		delta: u64,
+	},
+	AddOk {
+		in_reply_to: u64,
+	},
+	//SEQ-KV
+	Write {
+		msg_id: u64,
+		key: String,
+		value: u64,
+	},
+	WriteOk {
 		in_reply_to: u64,
 	},
 }
@@ -43,15 +54,24 @@ enum Body {
 fn main() {
 	let stdin = io::stdin();
 	let mut stdout = io::stdout();
+	let mut stderr = io::stderr();
+
+	let mut id = String::new();
 
 	for line in stdin.lock().lines() {
 		let input: Message = serde_json::from_str(&line.unwrap()).unwrap();
 		match input.body {
+			Body::Error { text, .. } => {
+				let output_json = serde_json::to_string(&text).unwrap();
+				writeln!(stderr, "{}", output_json).unwrap();
+				stdout.flush().unwrap();
+			}
 			Body::Init {
 				msg_id, node_id, ..
 			} => {
+				id = node_id.clone();
 				let output = Message {
-					src: node_id.clone(),
+					src: id.clone(),
 					dest: input.src,
 					body: Body::InitOk {
 						in_reply_to: msg_id,
@@ -59,9 +79,49 @@ fn main() {
 				};
 				let output_json = serde_json::to_string(&output).unwrap();
 				writeln!(stdout, "{}", output_json).unwrap();
+
+				let output = Message {
+					src: id.clone(),
+					dest: "seq-kv".to_string(),
+					body: Body::Write {
+						msg_id: 1,
+						key: "TEST".to_string(),
+						value: 42,
+					},
+				};
+				let output_json = serde_json::to_string(&output).unwrap();
+				writeln!(stdout, "{}", output_json).unwrap();
 				stdout.flush().unwrap();
 			}
-			_ => (),
+			Body::Read { msg_id } => {
+				let output = Message {
+					src: id.clone(),
+					dest: input.src,
+					body: Body::ReadOk {
+						in_reply_to: msg_id,
+						value: 42,
+					},
+				};
+				let output_json = serde_json::to_string(&output).unwrap();
+				writeln!(stdout, "{}", output_json).unwrap();
+				stdout.flush().unwrap();
+			}
+			Body::Add { msg_id, .. } => {
+				let output = Message {
+					src: id.clone(),
+					dest: input.src,
+					body: Body::AddOk {
+						in_reply_to: msg_id,
+					},
+				};
+				let output_json = serde_json::to_string(&output).unwrap();
+				writeln!(stdout, "{}", output_json).unwrap();
+				stdout.flush().unwrap();
+			}
+			Body::WriteOk { .. } => {
+				//
+			}
+			_ => println!("Unhandled message: {:?}", input),
 		}
 	}
 }