diff --git a/u01/.classpath b/u01/.classpath
deleted file mode 100644
index 5d3c3f5..0000000
--- a/u01/.classpath
+++ /dev/null
@@ -1,10 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<classpath>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/bellsoft-java11-full-amd64">
-		<attributes>
-			<attribute name="module" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry kind="src" path="src"/>
-	<classpathentry kind="output" path="bin"/>
-</classpath>
diff --git a/u01/.gitignore b/u01/.gitignore
deleted file mode 100644
index ae3c172..0000000
--- a/u01/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/bin/
diff --git a/u01/.project b/u01/.project
deleted file mode 100644
index 4fb1a78..0000000
--- a/u01/.project
+++ /dev/null
@@ -1,17 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<projectDescription>
-	<name>u01</name>
-	<comment></comment>
-	<projects>
-	</projects>
-	<buildSpec>
-		<buildCommand>
-			<name>org.eclipse.jdt.core.javabuilder</name>
-			<arguments>
-			</arguments>
-		</buildCommand>
-	</buildSpec>
-	<natures>
-		<nature>org.eclipse.jdt.core.javanature</nature>
-	</natures>
-</projectDescription>
diff --git a/u01/.settings/org.eclipse.core.resources.prefs b/u01/.settings/org.eclipse.core.resources.prefs
deleted file mode 100644
index 99f26c0..0000000
--- a/u01/.settings/org.eclipse.core.resources.prefs
+++ /dev/null
@@ -1,2 +0,0 @@
-eclipse.preferences.version=1
-encoding/<project>=UTF-8
diff --git a/u01/.settings/org.eclipse.jdt.core.prefs b/u01/.settings/org.eclipse.jdt.core.prefs
deleted file mode 100644
index f2525a8..0000000
--- a/u01/.settings/org.eclipse.jdt.core.prefs
+++ /dev/null
@@ -1,14 +0,0 @@
-eclipse.preferences.version=1
-org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=11
-org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
-org.eclipse.jdt.core.compiler.compliance=11
-org.eclipse.jdt.core.compiler.debug.lineNumber=generate
-org.eclipse.jdt.core.compiler.debug.localVariable=generate
-org.eclipse.jdt.core.compiler.debug.sourceFile=generate
-org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
-org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
-org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
-org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
-org.eclipse.jdt.core.compiler.release=enabled
-org.eclipse.jdt.core.compiler.source=11
diff --git a/u02/.classpath b/u02/.classpath
deleted file mode 100644
index d54800d..0000000
--- a/u02/.classpath
+++ /dev/null
@@ -1,10 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<classpath>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11">
-		<attributes>
-			<attribute name="module" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry kind="src" path="src"/>
-	<classpathentry kind="output" path="bin"/>
-</classpath>
diff --git a/u02/.gitignore b/u02/.gitignore
deleted file mode 100644
index ae3c172..0000000
--- a/u02/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/bin/
diff --git a/u02/.project b/u02/.project
deleted file mode 100644
index f5dbada..0000000
--- a/u02/.project
+++ /dev/null
@@ -1,17 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<projectDescription>
-	<name>u02</name>
-	<comment></comment>
-	<projects>
-	</projects>
-	<buildSpec>
-		<buildCommand>
-			<name>org.eclipse.jdt.core.javabuilder</name>
-			<arguments>
-			</arguments>
-		</buildCommand>
-	</buildSpec>
-	<natures>
-		<nature>org.eclipse.jdt.core.javanature</nature>
-	</natures>
-</projectDescription>
diff --git a/u02/.settings/org.eclipse.core.resources.prefs b/u02/.settings/org.eclipse.core.resources.prefs
deleted file mode 100644
index 99f26c0..0000000
--- a/u02/.settings/org.eclipse.core.resources.prefs
+++ /dev/null
@@ -1,2 +0,0 @@
-eclipse.preferences.version=1
-encoding/<project>=UTF-8
diff --git a/u02/.settings/org.eclipse.jdt.core.prefs b/u02/.settings/org.eclipse.jdt.core.prefs
deleted file mode 100644
index f2525a8..0000000
--- a/u02/.settings/org.eclipse.jdt.core.prefs
+++ /dev/null
@@ -1,14 +0,0 @@
-eclipse.preferences.version=1
-org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=11
-org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
-org.eclipse.jdt.core.compiler.compliance=11
-org.eclipse.jdt.core.compiler.debug.lineNumber=generate
-org.eclipse.jdt.core.compiler.debug.localVariable=generate
-org.eclipse.jdt.core.compiler.debug.sourceFile=generate
-org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
-org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
-org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
-org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
-org.eclipse.jdt.core.compiler.release=enabled
-org.eclipse.jdt.core.compiler.source=11
diff --git a/u03/.classpath b/u03/.classpath
deleted file mode 100644
index d54800d..0000000
--- a/u03/.classpath
+++ /dev/null
@@ -1,10 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<classpath>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11">
-		<attributes>
-			<attribute name="module" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry kind="src" path="src"/>
-	<classpathentry kind="output" path="bin"/>
-</classpath>
diff --git a/u03/.gitignore b/u03/.gitignore
deleted file mode 100644
index ae3c172..0000000
--- a/u03/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/bin/
diff --git a/u03/.project b/u03/.project
deleted file mode 100644
index caf1bf2..0000000
--- a/u03/.project
+++ /dev/null
@@ -1,17 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<projectDescription>
-	<name>u03</name>
-	<comment></comment>
-	<projects>
-	</projects>
-	<buildSpec>
-		<buildCommand>
-			<name>org.eclipse.jdt.core.javabuilder</name>
-			<arguments>
-			</arguments>
-		</buildCommand>
-	</buildSpec>
-	<natures>
-		<nature>org.eclipse.jdt.core.javanature</nature>
-	</natures>
-</projectDescription>
diff --git a/u03/.settings/org.eclipse.core.resources.prefs b/u03/.settings/org.eclipse.core.resources.prefs
deleted file mode 100644
index 99f26c0..0000000
--- a/u03/.settings/org.eclipse.core.resources.prefs
+++ /dev/null
@@ -1,2 +0,0 @@
-eclipse.preferences.version=1
-encoding/<project>=UTF-8
diff --git a/u03/.settings/org.eclipse.jdt.core.prefs b/u03/.settings/org.eclipse.jdt.core.prefs
deleted file mode 100644
index f2525a8..0000000
--- a/u03/.settings/org.eclipse.jdt.core.prefs
+++ /dev/null
@@ -1,14 +0,0 @@
-eclipse.preferences.version=1
-org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=11
-org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
-org.eclipse.jdt.core.compiler.compliance=11
-org.eclipse.jdt.core.compiler.debug.lineNumber=generate
-org.eclipse.jdt.core.compiler.debug.localVariable=generate
-org.eclipse.jdt.core.compiler.debug.sourceFile=generate
-org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
-org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
-org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
-org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
-org.eclipse.jdt.core.compiler.release=enabled
-org.eclipse.jdt.core.compiler.source=11
diff --git a/u04/.classpath b/u04/.classpath
deleted file mode 100644
index d54800d..0000000
--- a/u04/.classpath
+++ /dev/null
@@ -1,10 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<classpath>
-	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11">
-		<attributes>
-			<attribute name="module" value="true"/>
-		</attributes>
-	</classpathentry>
-	<classpathentry kind="src" path="src"/>
-	<classpathentry kind="output" path="bin"/>
-</classpath>
diff --git a/u04/.gitignore b/u04/.gitignore
deleted file mode 100644
index ae3c172..0000000
--- a/u04/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/bin/
diff --git a/u04/.project b/u04/.project
deleted file mode 100644
index ff02c53..0000000
--- a/u04/.project
+++ /dev/null
@@ -1,17 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<projectDescription>
-	<name>u04</name>
-	<comment></comment>
-	<projects>
-	</projects>
-	<buildSpec>
-		<buildCommand>
-			<name>org.eclipse.jdt.core.javabuilder</name>
-			<arguments>
-			</arguments>
-		</buildCommand>
-	</buildSpec>
-	<natures>
-		<nature>org.eclipse.jdt.core.javanature</nature>
-	</natures>
-</projectDescription>
diff --git a/u04/.settings/org.eclipse.core.resources.prefs b/u04/.settings/org.eclipse.core.resources.prefs
deleted file mode 100644
index 99f26c0..0000000
--- a/u04/.settings/org.eclipse.core.resources.prefs
+++ /dev/null
@@ -1,2 +0,0 @@
-eclipse.preferences.version=1
-encoding/<project>=UTF-8
diff --git a/u04/.settings/org.eclipse.jdt.core.prefs b/u04/.settings/org.eclipse.jdt.core.prefs
deleted file mode 100644
index f2525a8..0000000
--- a/u04/.settings/org.eclipse.jdt.core.prefs
+++ /dev/null
@@ -1,14 +0,0 @@
-eclipse.preferences.version=1
-org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
-org.eclipse.jdt.core.compiler.codegen.targetPlatform=11
-org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
-org.eclipse.jdt.core.compiler.compliance=11
-org.eclipse.jdt.core.compiler.debug.lineNumber=generate
-org.eclipse.jdt.core.compiler.debug.localVariable=generate
-org.eclipse.jdt.core.compiler.debug.sourceFile=generate
-org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
-org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
-org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
-org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=warning
-org.eclipse.jdt.core.compiler.release=enabled
-org.eclipse.jdt.core.compiler.source=11