===========================
[[1, 1, 2, 2]] ----- 
 []
===========================
[[2, 0, 0, 2], [0, 2, 2, 0], [2, 0, 2, 0], [0, 2, 0, 2]] ----- 
 [[0, 1], [2, 3]]

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===========================
[[2, 0, 1, 1, 2, 0], [2, 0, 1, 0, 1, 2], [1, 0, 1, 2, 2, 0], [2, 0, 1, 0, 2, 1], [0, 0, 1, 2, 1, 2], [0, 0, 1, 2, 2, 1], [2, 0, 1, 2, 0, 1], [0, 0, 1, 1, 2, 2], [1, 0, 1, 0, 2, 2], [2, 0, 1, 2, 1, 0], [1, 0, 1, 2, 0, 2], [2, 0, 1, 1, 0, 2]] -----
 [[0, 3, 4, 5]]

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===========================
[[2, 1, 0, 2, 0, 2, 0], [1, 2, 0, 2, 0, 0, 2], [1, 2, 0, 2, 0, 2, 0], [2, 1, 0, 2, 0, 0, 2], [2, 1, 0, 0, 2, 0, 2], [2, 1, 0, 0, 2, 2, 0], [1, 2, 0, 0, 2, 0, 2], [1, 2, 0, 0, 2, 2, 0]] -----
 [[0, 1], [3, 4], [5, 6]]
===========================
[[1, 2, 0, 2, 0, 0, 2], [1, 2, 0, 2, 0, 2, 0], [1, 0, 2, 2, 0, 0, 2], [1, 2, 0, 0, 2, 2, 0], [1, 0, 2, 0, 2, 0, 2], [1, 0, 2, 2, 0, 2, 0], [1, 2, 0, 0, 2, 0, 2], [1, 0, 2, 0, 2, 2, 0]] -----
 [[1, 2], [3, 4], [5, 6]]
===========================
[[1, 2, 1, 2, 0, 2, 0], [1, 2, 1, 0, 2, 2, 0], [1, 2, 1, 0, 2, 0, 2], [1, 2, 1, 2, 0, 0, 2]] -----
 [[3, 4], [5, 6]]

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===========================
[[2, 1, 0, 1, 0], [1, 2, 0, 1, 0], [1, 2, 0, 0, 1], [2, 1, 0, 0, 1]] -----
 [[0, 1], [3, 4]]
===========================
[[1, 2, 0, 0, 1], [1, 0, 2, 0, 1]] -----
 [[1, 2]]

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===========================
[[2, 1, 0, 1, 0], [1, 2, 0, 1, 0]] -----
 [[0, 1]]
===========================
[[1, 2, 0, 0, 1], [1, 0, 2, 0, 1]] -----
 [[1, 2]]