Get default gateway address when openvpn run with --route-nopull

[t1m013y]

I want to make a custom script that will launch openvpn with --route-nopull and configure custom routing scheme for it. I need a local ip, a server ip and a default gateway address for it. I can find local ip and server ip in the openvpn control protocol (state command), but I can't find default gateway address. How can I get it (I need a way that can be automatically done by the script)?