如何通过serversfree中的cron作业执行php脚本？

I tried to make a cron job but it didn't execute the script.

Screenshots here:

What command do I need to execute to make the script execute every 30 minutes?

Thanks

I figured it out, I need to add public_html to the command: php -f /home/u757823165/public_html/cron/save.php