% ruby sim.rb simulate pub1.in 
Train Red 1 entering Glenmont
Train Red 1 leaving Glenmont
Train Red 1 entering Silver Spring
Train Red 1 leaving Silver Spring
Train Red 1 entering Union Station
Train Red 1 leaving Union Station
Train Red 1 entering Bethesda
Train Red 1 leaving Bethesda
Train Red 1 entering Shady Grove
Train Red 1 leaving Shady Grove
Train Red 1 entering Bethesda
Train Red 1 leaving Bethesda
Train Red 1 entering Union Station
Train Red 1 leaving Union Station
Train Red 1 entering Silver Spring
Train Red 1 leaving Silver Spring
Train Red 1 entering Glenmont
Train Red 1 leaving Glenmont