Train Leaving Gray

|--6---6---4---3---3---3---3---3-----------------------------------|
|--6---6---4---4---4---4---4---4--4---4---4---4---6---6---7---7----|
|--3-------4-------5-------6------5---5---5---5---7---7---7---7----|
|---------------------------------6-------6-------8-------8--------|
|------------------------------------------------------------------|
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