On the eve of the holidays, you are going to hang two strings of colorful lights on the tree in front of your house. The first flashing of the two strings of colored lights are independent of each other, and may occur at any time uniformly within 4 seconds after power-on, and then each string of colored lights flashes at an interval of 4 seconds. If the two strings of colored lights are energized at the same time, what is the probability that the difference between their first flashing moments is no more than 2 seconds?