diff --git a/app/src/main/java/edu/sharif/prj01/NotThreadSafe.java b/app/src/main/java/edu/sharif/prj01/NotThreadSafe.java
index 19056ae..b552c9b 100644
--- a/app/src/main/java/edu/sharif/prj01/NotThreadSafe.java
+++ b/app/src/main/java/edu/sharif/prj01/NotThreadSafe.java
@@ -2,11 +2,17 @@
 
 public class NotThreadSafe{
     StringBuilder builder = new StringBuilder();
+    static StringBuilder staticBuilder = new StringBuilder();
+
 
     public void add(String text){
         this.builder.append(text);
     }
 
+    public void addToStaticBuilder(String text){
+        staticBuilder.append(text);
+    }
+
     public static class MyRunnable implements Runnable{
         NotThreadSafe instance = null;
 
@@ -18,4 +24,16 @@ public void run(){
             this.instance.add("some text");
         }
     }
+
+    public static class MyRunnablePrime implements Runnable{
+        NotThreadSafe instance = null;
+
+        public MyRunnablePrime(NotThreadSafe instance){
+            this.instance = instance;
+        }
+
+        public void run(){
+            this.instance.addToStaticBuilder("some text");
+        }
+    }
 }
\ No newline at end of file