One can escape the shell input prompt by using the grave character (``` ` ```) then the command to run and then another grave character to close.

Here are the steps to solving this challenge:

1. Input ``` `ls` ``` to find the correct file (it's just in the same directory, so nothing more is needed to be done):

Output: `< bin flag lib lib64 server.py usr >`

2. Input ``` `strings flag` ``` to read the flag file (using `cat` is disabled):

Output: `< justCTF{p0nY_t4lEs_b3giN5_h3r3} >`