diff --git a/src/main/java/Proto/A.java b/src/main/java/Proto/A.java
index 8ca3795..3453fb1 100644
--- a/src/main/java/Proto/A.java
+++ b/src/main/java/Proto/A.java
@@ -1,5 +1,13 @@
 package Proto;
 
 public class A {
+	protected int a;
 
+	public int get() {
+		return a;
+	}
+
+	public void set(int a) {
+		this.a = a;
+	}
 }
diff --git a/src/main/java/Proto/B.java b/src/main/java/Proto/B.java
index bd01afb..ec8b492 100644
--- a/src/main/java/Proto/B.java
+++ b/src/main/java/Proto/B.java
@@ -1,5 +1,5 @@
 package Proto;
 
-public class B {
+public class B extends A {
 
 }
diff --git a/src/main/java/Proto/C.java b/src/main/java/Proto/C.java
index 3e7755b..b84d714 100644
--- a/src/main/java/Proto/C.java
+++ b/src/main/java/Proto/C.java
@@ -1,5 +1,5 @@
 package Proto;
 
-public class C {
+public class C extends A{
 
 }
diff --git a/src/main/java/Proto/D.java b/src/main/java/Proto/D.java
index c457b4f..780f3d8 100644
--- a/src/main/java/Proto/D.java
+++ b/src/main/java/Proto/D.java
@@ -1,5 +1,5 @@
 package Proto;
 
-public class D {
+public class D extends A{
 
 }