--- /dev/null
+<html><head/><body><h1>a1.html</h1></body></html>
--- /dev/null
+<html><head/><body><h1>a2.html</h1></body></html>
--- /dev/null
+<html><head/><body><h1>a3.html</h1></body></html>
--- /dev/null
+<html><head/><body><h1>b1.html</h1></body></html>
--- /dev/null
+<html><head/><body><h1>b2.html</h1></body></html>
--- /dev/null
+<html><head/><body><h1>b3.html</h1></body></html>