please complete the following exercise using JAVA and the method header:

public static int countPairs(List numbers, int k)

1. Counting Pairs Given an integer k and a list of integers, count the number of distinct valid pairs of integers (a, b) in the list for which a + k = b. Two pairs of integers (a, b) and (d) are considered distinct if at least one element of (a, b) does not also belong to (cd). Example n4 numbers = [1,1,1,21 K = 7 This array has two different valid pairs: (1.1) and (1, 2). For k = 1, there is only 7 valid pair which satisfies 0 + k = b: the pair (a, b) = (1.2). Function Description Complete the function count Pairs in the editor below. countPairs has the following parameter(s): int numbers in: array of integers int k: target difference Returns int: number of valid (a, b) pairs in the numbers array that have a difference of k Constraints - 2 sn s 2 x 10 . 0 numbers(i) s 10' where 0 sian Osks 10 Input Format for Custom Testing Input rom stain will be processed as follows and passed to the function The first line contains an integer n, the size of the array numbers. Each of the next n lines contains an integer numbers[l] where 0 si<.>