This is a very basic simulation of an epidemic. We begin with `nb_ppl`

infected people.

`crit_dist`

-- the distance needed to potentially get infected. We then sample from a \(\text{Ber}(p) \) distribution to determine if the person will get infected or not, where `p`

is chosen by the user below.
Total number of infected indviduals:

Select the population size.

Now we need to determine the probability that one person infects someone else. Choose a value in \( ]0, 1] \).