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xxxxxx  f    xxxxx
xxxx      f hrrxxx
xxxr       f rrrxx
xxx      f   rrrxx
xxr              x
xxr   f   f      x
xxrr             x
xxrr  f p        x
xx      f       fx
xx f      f      x
xx               x
xxx f           xx
xxx         f   xx
xxxx          hxxx
xxxxxxrr     xxxxx
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