n=Scanf_Int();
        m=Scanf_Int();
       int[] a=new int[n+1];
       for (int i=1;i<=n;i++){
           a[i]=Scanf_Int();
       }
        for (int i=1;i<=n;i++){
            for (int j=1;j<=n;j++){
                if (i==j){
                    continue;
                }
                if (Math.abs(a[i]-a[j])<=m){
                    ans++;
                }
            }
        }
        out.println(ans);