Source there is one source in the system it is represented by district character since they're an Albert number six in the system they are each represented by different uppercase ABC etc. pops there are $10$ different shades of popes represented by the following characters note that each pope has openings on two or three sides of itself to adjacent cells are connected if both have a pop opening at the shared edge for example the two cells are connected to each other through the stair edge the two cells are not connected to each other through their stared edge but they could possibly still be connected via a path through other cells around them treat the source and stink as having open popes all ages for example the two cells are connected through their shared edge but the two cells are not directly connected to the shared edge a sink may be connected to the source through another sink for example the simple pop system all three are connected to the source group objective is a function that determines what sink are connected to the source and given pop system