function changeCategory () {
	for ( i = 0; i < document.create_advertisement.category.length; i++ ) {
		if ( document.create_advertisement.category[i].checked ) {
			if ( document.create_advertisement.category[i].value == 1 ) {
				document.create_advertisement.price.disabled = true;
				document.create_advertisement.end_price.disabled = true;
				document.create_advertisement.image.disabled = false;
			} else if ( document.create_advertisement.category[i].value == 2 ) {
				document.create_advertisement.price.disabled = false;
				document.create_advertisement.end_price.disabled = false;
				document.create_advertisement.image.disabled = true;
			} else if ( document.create_advertisement.category[i].value == 3 ) {
				document.create_advertisement.price.disabled = false;
				document.create_advertisement.end_price.disabled = true;
				document.create_advertisement.image.disabled = false;
			}
		}
	}
}