diff --git a/docs/book/24-Concurrent-Programming.md b/docs/book/24-Concurrent-Programming.md
index baa79c7b..b24e4569 100644
--- a/docs/book/24-Concurrent-Programming.md
+++ b/docs/book/24-Concurrent-Programming.md
@@ -360,8 +360,9 @@ public class Summing {
         else
             System.out.format("result: %d%ncheckValue: %d%n", result, checkValue);
         }
-    public static final int SZ = 100_000_000;// This even works://
-    public static final int SZ = 1_000_000_000;
+    public static final int SZ = 100_000_000;
+    // This even works:
+    // public static final int SZ = 1_000_000_000;
     public static final long CHECK = (long)SZ * ((long)SZ + 1)/2; // Gauss's formula
     public static void main(String[] args){
         System.out.println(CHECK);
@@ -3159,4 +3160,4 @@ Pizza4: complete
 
 <!-- 分页 -->
 
-<div style="page-break-after: always;"></div>
\ No newline at end of file
+<div style="page-break-after: always;"></div>