G
____0_0_0__
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|_|_|_|_|_|
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|_1_|_|_|_|
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2_|_|_|_|_3
C
x_____0___0
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|_|_|_|_1_|
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|_|_2_|_|_|
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|_3_|_|_|_|
D
x_x_0______
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|_|_|_|_|_|
| | | | | |
|_|_|_1_|_2
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|_|_|_|_3_|
| | |