~ are for bit inversion 
use my example, or in short if you want the solution without thinking 
:
:put [/ip route find dst-address=0.0.0.0/0 (routing-mark)."" = ""]
~ are for bit inversion
use my example, or in short if you want the solution without thinking :
:put [/ip route find dst-address=0.0.0.0/0 (routing-mark)."" = ""]