WELCOME to JF's ZONE

class Quis13
{
  public static void main(String[] args)
  {
    int n = Integer.parseInt(javax.swing.JOptionPane.showInputDialog("Masukkan nilai N:"));
    int baris = 0;
    int kolom = 0;
    int status = 0;

    for (baris=1; baris<=n; baris++)
    {
      for (kolom=1; kolom<=2*n; kolom++)
      {
        if (status == 0)
          System.out.print((char)219);
        else
          System.out.print(" ");

        if (kolom < 2*n)
          status = status++ % 2;
      }
      System.out.println();
    }
  }
}