Pink= Infected Green=Recovered Yellow= Healthy at beginning. Green can get sick again but there's a lower chance of it happening. But in the end everyone got sick over time. If the pink hits a green they will get sick but there will always be a sick ball. But because of there not being that many balls it is a lower chance. The number of balls is a normal amount of people in a classroom including the teacher. This is over the days from all of the moving around. How to start. All you need to do is press the green start flag to start the code.