public class lacos
{
   public static void main(String args[])
   {
      int i = 0;
      while(i<4)
      {
         int x = 0;
         while(x<4)
         {
            System.out.println( i + "  " + x );
            x = x + 1;
         }
         i = i + 1;
      }
   }
}