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tttttttttttttttttttttttttttttttttttttt
tt-----------------------------------t
ttt-tttttttttttttttttttttttttttttttt-t
ttt-tt----tttttttttttttttttttttttttt-t
ttt----tt-tttttttttttttttttttttttttt-t
ttt-ttttt-tttttttttttttttttttttt---t-t
tt--------tttttttttttttttttttttt-ttt-t
tt-ttttttttt----ttttt---t-----tt-tt--t
tt-ttttttttt-tt-ttttt-t-t-ttt-tt-ttt-t
tt-ttttttttt-tt-------t---ttt-tt-ttt-t
tt-----------tttttttttttttttt-t--ttt-t
tttt-ttttttttttttttttttttt------tttt-t
tttt-ttttttttttttttttttttt-ttttttttt-t
tttt-ttt----------ttttt----ttttttttt-t
tttt-----tttttttt-------tttttttttttt-t
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