/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		int arr[] = {1,2,3,1,2,4};
		int n = arr.length;
		int k = 1;
		int count = 0;
 
		for(int i = 0;i<n;i++){
			for(int j = i+1;j<n;j++){
				int difference = (arr[i] - arr[j]);
				if( difference== k){
					count++;
				}
			}
		}
       System.out.println(count);
	}
 
}

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