Exercise 4. A group of 20 dwarves coming out of the mine sit around a round table to count the gold nuggets each has mined. They make the following observations:

$\triangleright$ The difference in the number of nuggets between two neighboring dwarves is always 2 or 3.

$\triangleright$ All the dwarves have mined a different number of nuggets.

What is the greatest possible difference in nuggets between the dwarf who found the most and the one who found the least?