Assume you want to clean the floor of a room using 3 robotic vacuum cleaners that can work in parallel. The floor is discretized into a $5\times 5$ grid. Each cell can be either clean or dirty. A binary state variable is used to represent whether a specific cell is clean or dirty. A robot can be in exactly one cell and several robots can be in the same cell. For every robot, there is a state variable whose values represent the location of the specific robot. Every robot has $5$ charge levels, a robots actions costs one charge, and there are recharging stations present at the room. We use a state variable to represent the charge level of every robot. What is the number of possible states in the state space of the problem?

A reasonable time to generate a state is $10^{-6}$ seconds. With this assumption, how many years (rounded to a natural number) does it take to generate all the possible states in the state space from the previous exercise?