And finally the solution:
disable ICMP echo reply "destination host unreachable" on router.

/ip firewall filter add protocol=icmp icmp-options=3 chain=output action=drop

now there are no replies from router if host unreachable, so count=0!

Hi, gents! Sorry for digging into very old post, but hope someone can reply still. I have a problem with this script as it's based on presumption that there will be no any reply on ping. In fact, 4 of 5 pings die without reply and 1 out of 5 is replied by router itself with "host unreachable&qu...