What are the three hands of a printing offset press for?

In the printing factory, the offset press operator has other assistants besides the captain. What are the three hands for? Supplement: Sorry, the left-handed prince doesn't understand the operation of offset press. Your answer is not acceptable. Supplement: I have been operating offset press for 10 years. Generally speaking, each machine has more than two people. As far as I know, even the most advanced multi-color machine made in Germany needs more than two people, let alone how much is used? Most printing houses in China are still slightly (earlier) machines, which need about three people. Machines with more than four colors, 10 meters long, are too busy for two people. It's just that the titles and responsibilities of some areas are not clear. For example, some areas are called: Captain, Big Help, Second Help, etc. For example, the captain is in charge of everything, which greatly helps to load and unload kanban ink, and secondly helps to control paper feeding. Supplement: you are a four-open monochrome machine, which can't be compared with a multi-color machine. This question is not easy to say here. You can chat and discuss with your friends. I look forward to the answer from Jiangnan netizens who understand the division of labor of operators on big machines.