diff --git a/_example/blockchain.pdf b/_example/blockchain.pdf
index 0bcd5be..3e7f280 100644
Binary files a/_example/blockchain.pdf and b/_example/blockchain.pdf differ
diff --git a/_example/client.go b/_example/client.go
index 8f3efd4..8d2685e 100644
--- a/_example/client.go
+++ b/_example/client.go
@@ -125,6 +125,8 @@ func handleClient() {
     userPurse()
    case "balance":
     userBalance()
+   default:
+    fmt.Println("command undefined\n")
    }
   case "/chain":
    if len(splited) < 2 {
@@ -138,6 +140,12 @@ func handleClient() {
     chainTX(splited[1:])
    case "balance":
     chainBalance(splited[1:])
+   case "block":
+    chainBlock(splited[1:])
+   case "size":
+    chainSize()
+   default:
+    fmt.Println("command undefined\n")
    }
   default:
    fmt.Println("command undefined\n")
@@ -219,6 +227,38 @@ func chainBalance(splited []string) {
  printBalance(splited[1])
 }
 
+func chainBlock(splited []string) {
+ if len(splited) != 2 {
+  fmt.Println("failed: len(splited) != 2\n")
+  return
+ }
+ num, err := strconv.Atoi(splited[1])
+ if err != nil {
+  fmt.Println("failed: strconv.Atoi(num)\n")
+  return
+ }
+ res := nt.Send(Addresses[0], &nt.Package{
+  Option: GET_BLOCK,
+  Data:   fmt.Sprintf("%d", num-1),
+ })
+ if res == nil || res.Data == "" {
+  fmt.Println("failed: getBlock\n")
+  return
+ }
+ fmt.Printf("[%d] => %s\n", num, res.Data)
+} 
+
+func chainSize() {
+ res := nt.Send(Addresses[0], &nt.Package{
+  Option: GET_CSIZE,
+ })
+ if res == nil || res.Data == "" {
+  fmt.Println("failed: getSize\n")
+  return
+ }
+ fmt.Printf("Size: %s blocks\n\n", res.Data)
+}
+
 func printBalance(useraddr string) {
  for _, addr := range Addresses {
   res := nt.Send(addr, &nt.Package{
@@ -226,7 +266,7 @@ func printBalance(useraddr string) {
    Data:   useraddr,
   })
   if res == nil {
-    continue
+   continue
   }
   fmt.Printf("Balance (%s): %s coins\n", addr, res.Data)
  }
@@ -239,6 +279,7 @@ const (
  GET_BLOCK       
  GET_LHASH    
  GET_BLNCE   
+ GET_CSIZE
 )
 
 func main() {
diff --git a/_example/node.go b/_example/node.go
index 94bacb3..5aaab27 100644
--- a/_example/node.go
+++ b/_example/node.go
@@ -64,6 +64,7 @@ const (
  GET_BLOCK       
  GET_LHASH    
  GET_BLNCE   
+ GET_CSIZE
 )
 
 func init() {
@@ -191,6 +192,7 @@ func handleServer(conn nt.Conn, pack *nt.Package) {
  nt.Handle(GET_BLOCK, conn, pack, getBlock)
  nt.Handle(GET_LHASH, conn, pack, getLastHash)
  nt.Handle(GET_BLNCE, conn, pack, getBalance)
+ nt.Handle(GET_CSIZE, conn, pack, getChainSize)
 }
 
 func addBlock(pack *nt.Package) string {
@@ -273,6 +275,10 @@ func getBalance(pack *nt.Package) string {
  return fmt.Sprintf("%d", Chain.Balance(pack.Data, Chain.Size()))
 }
 
+func getChainSize(pack *nt.Package) string {
+ return fmt.Sprintf("%d", Chain.Size())
+}
+
 const (
  SEPARATOR = "_SEPARATOR_"
 )
diff --git a/client.go b/client.go
index 5d8d20d..09ba96a 100644
--- a/client.go
+++ b/client.go
@@ -90,6 +90,8 @@ func handleClient() {
 				userPurse()
 			case "balance":
 				userBalance()
+			default:
+    			fmt.Println("command undefined\n")
 			}
 		case "/chain":
 			if len(splited) < 2 {
@@ -107,6 +109,8 @@ func handleClient() {
 				chainBlock(splited[1:])
 			case "size":
 				chainSize()
+			default:
+    			fmt.Println("command undefined\n")
 			}
 		default:
 			fmt.Println("command undefined\n")
@@ -122,7 +126,7 @@ func chainSize() {
 		fmt.Println("failed: getSize\n")
 		return
 	}
-	fmt.Println("Size:", res.Data, "\n")
+	fmt.Printf("Size: %s blocks\n\n", res.Data)
 }
 
 func chainBlock(splited []string) {
@@ -137,7 +141,7 @@ func chainBlock(splited []string) {
 	}
 	res := nt.Send(Addresses[0], &nt.Package{
 		Option: GET_BLOCK,
-		Data:   fmt.Sprintf("%d", num),
+		Data:   fmt.Sprintf("%d", num-1),
 	})
 	if res == nil || res.Data == "" {
 		fmt.Println("failed: getBlock\n")
@@ -231,5 +235,5 @@ func userBalance() {
 func inputString(begin string) string {
 	fmt.Print(begin)
 	msg, _ := bufio.NewReader(os.Stdin).ReadString('\n')
-	return strings.Replace(msg, "\r\n", "", 1)
+	return strings.Replace(msg, "\n", "", 1)
 }