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xxxxxx      rxxxxx
xxxx  f     rrrxxx
xxxr       f f fxx
xxxrrr     f    xx
xx frr     f     x
xx  rr   rrr     x
xx  f    rrr     x
xx               x
xx               x
xx       p       x
xx           rrrrx
xxx    frrrrrrrrxx
xxx    rrrrrrrrrxx
xxxx  rrrrrrrrrxxx
xxxxxxrrrrrrrxxxxx
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