new
empty 1
size 0
front!
back!
height -1
member  5 0
member 10 0
member 15 0
insert 10 1
empty 0
size 1
front 10
back 10
height 0
member  5 0
member 10 1
member 15 0
insert 10 0
insert  5 1
empty 0
size 2
front 5
back 10
height 1
member  5 1
member 10 1
member 15 0
insert 15 1
empty 0
size 3
front 5
back 15
height 1
member  5 1
member 10 1
member 15 1
traverse
insert 7 1
insert 6 1
size 5
height 3
traverse
erase 5 1
erase 5 0
front 6
erase 7 1
front 6
traverse
erase 6 1
front 10
erase 10 1
front 15
back 15
height 3
traverse
erase 6 0
delete
summary
exit