L
L
D
1
x
-
x
x x
x
x
-
x
x
x
x
x
-
x
x
x
x
x
x
-
x
x
x
x
x
x
-
x
x
x
x
-
x
x
x
x
x
-
x
x
x
-
x
x
x
x
x
x
x
x
x
x
x
-
x
x
