backwards 30/60 AND:
60 20/
| 30
V | / ---30/60---> X[in]
Z[out] ---30/60---> M <---30/0--- SS ---20/30/60---> M ---60/90/120---> S
sink <---60--- / overflow^ | \ ---30/60---> Y[in]
20/
30

if it works, it works



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