How to stop script

RouterOS Scripting
1

Hello,
I use script for configure Mikrotik.
After enable DHCP-Client, I configure NTP server and check last sync:

:do {:delay 1} while=([/system ntp client get last-update-before]=[]);

How I can stop script if Mikrotik can’t sync after 60 sec?
Thanks!

2 
:set counter 0
:do {:delay 1; :set $counter ($counter+1);} while=(([/system ntp client get last-update-before]=[]) and ($counter<60));