The police was somewhat confused: they didn't mind that much my repeated crossing, but they did mind putting stamps in the passport. I insisted on having them, for the record, but also for the fact that they would never miss a chance to put the stamp in a Yugoslav passport if one would cross in a regular way, even at the cost of a new page in the passport, which is considered as a great value for the owner of the passport - an empty page means a place for a new visa, which means freedom of movement.