After setup 3
thing 20
thing 10
thing 5

After clearing 0

After setup 3
thing 5
thing 10
thing 20

After clearing 0

After setting 7
thing 2
thing 4
thing 6
thing 0
thing 8
thing 10
thing 12

After removing 6
thing 4
thing 6
thing 0
thing 8
thing 10
thing 12

After removing 5
thing 4
thing 6
thing 8
thing 10
thing 12

After removing 4
thing 4
thing 6
thing 8
thing 10