Today, Léo the snail moved along the path from eight in the morning to six in the evening. Several people observed him on his journey: each stayed exactly one hour, and observed that Léo had moved exactly one meter. At any time during the day, there was at least one observer. What is the greatest distance that Léo could have traveled?
(solved by Anatole Bouton)

We will say that two observers see each other if they observe Léo for a non-zero duration together.

Let's try to maximize the distance traveled by Léo. If, at a certain moment, there are three observers $o_{1}, o_{2}, o_{3}$ at the same time, let's denote $h_{1}0, k \leq 8$, so we have a maximum distance traveled of $2+2 \cdot 8=18 \text{ m}$.

We achieve the value of $18 \text{ m}$ by taking 9 large observers who stay for a duration of $\frac{10}{9}>1$ hours and ensuring that Léo advances by $2 \text{ m}$ during the observation period of each observer.