____6_____opt.
____8_____4
____7_____2
____8_____3
____6_____1
__________x
____3_____3
____3_____3
____3_____3
____1_____1
__________x
__________x
__________x
____11____3
____12____4
____12____3
__________x
____11____1
__________
____15____4
____12____2
__________x
____13____3
____11____1
____15____3
____15____3
____15____3
____13____1
__________x
__________x
____10____1
____11____2
____12____3
____13____4
__________x
__________x
