/* 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
	{
		int[] towns = new int[]{1  , 5 ,  7 ,  8 ,  9 ,  11 ,  12};
		Arrays.sort(towns);
int count = 0;
int d = 3;
int i = towns.length-1;
int j = towns.length-2;
while(!(j==0 && towns[i]-towns[j] < d)){
	System.out.printf("%d - %d = %d\n",towns[i],towns[j],towns[i]-towns[j]);
	if(towns[i]-towns[j] == d) count++;
	if(towns[i]-towns[j] < d) j--;
	else i--;
}
 
System.out.println(count);
	}
}

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