You have three jars that hold max 19, 13 and 7 liters of water
respectively. 13 and 7 litre jars are full of water and 19 litre jar
is empty (so total 20 litres of water).
You can pour water between jars and I want two jars with 10
litres of water (ie 10, 10, 0 from 0, 13, 7)
