A simple ROP challenge.
A very detailed writeup can be found on [my website](https://syedfarazabrar.com/pwn/2019/06/22/hsctf-binary-exploitation-challenges.html#combo-chain-lite).
If you are confused as to how ROP (return oriented prrogramming) works, I also have writeups on the ROP Emporium challenges on my website, easily found under the Writeups section.