import java.util.*;
 
public class Main {
 
    public static int countPairs(int[] b, int k) {
        int count = 0;
        int n = b.length;
        for (int i = 0; i < n; ++i) {
            for (int j = i+1; j < n; ++j) {
                if (Math.abs(b[i] - b[j]) == k) {
                    count++;
                }
            }
        }
        return count;
    }
 
    public static void main(String[] args) {
        int[] b = {1, 7, 5, 9, 2, 12, 3};
        int k = 2;
        System.out.println("Number of pairs: " + countPairs(b, k));
    }
}

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