It is not enough to find the same letter at the same position (i.e. same time) during the walk,because the same letter can denote a different tree of the same kind. For example, both families ended their walk at a tree labeled A, but if we follow both walks step by step then we can find out that actually they ended at different trees.Note that we can follow each step of each family quite easily because the neighbours of each tree (the trees that are connected to it by a path) are always labeled with different letters. However, to follow the two walks in parallel is not that easy (but doable).So let’s mark out first the walk of the Wilde family (starting at F, by blue colour) and number the visited trees by the time in which they visited it (blue numbers 1 to 11). Then let’s mark out, in a similar way, the Gilde family walk with a red colour and red numbers.The two families would meet at some trees only if that tree were numbered by the same red and blue number. But we cannot see any such trees in our picture.Note that there are only two trees visited by both families, so we can focus only on those two.The tree D (the leftmost one in the park) was visited by the Wilde family only at time 7 and by the Gilde family at times 2, 4, 8 and 10. The tree E (the one neighbouring the leftmost D) wasvisited by Wilde family at time 6 and 8, but by the Gilde family only at time 9.