I have some difficulties in solving the following problem:

A deck of 52 playing cards, containing all 4 aces, is randomly divided into 4 piles of 13 cards each. Define events E1, E2, E3, E4 as follows:

E1 = {the first pile has exactly 1 ace},

E2 = {the second pile has exactly 1 ace},

E3 = {the third pile has exactly 1 ace},

E4 = {the fourth pile has exactly 1 ace},

Use the formula

to find

the probability that each pile has an ace.