diff --git a/lec14/report14.md b/lec14/report14.md
index 788516a9c0afb0281159047f2dc09d3492e39596..cc6b80a13e85b5e13c47a9cd64d38a0e01902aef 100644
--- a/lec14/report14.md
+++ b/lec14/report14.md
@@ -27,4 +27,10 @@
     * block <br>
 ![lec14-2](../Image/lec14-2.jpg)    
 
+### How to control static and global variable?
+* static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZERS;
+
+    pthread_mutex_lock(&mutex);
+    count++;
+    pthread_mutex_unlock(&mutex);