Two dogs are in front of your house. The first barking of the two dogs are independent of each other, and may occur at any time uniformly within 4 seconds after opening the door, and then each dog barks at an interval of 4 seconds. If the two dogs both notice you opening the door at the same time, what is the probability that the difference between their first barking moments is no more than 2 seconds?
$f(x) = \int probability(>) , 0<x<4 $
i know that the uniform distribution is bounded by 0 and 4,
but i do not know what to do to go further from this question
Honestly very lost and do not know where to start

Here is a hint, which may help