Original writeup [here](https://borelenzo.github.io/CTFs/red_pwn_19/l_star/)

We were given three files: l_star.c, nay.txt and yay.txt. We had to find a regex that could match all lines in yay.txt and none of them in nay.txt. We noticed that all lines in yay.txt ended with "aba", but it was never the case in nay.txt. The regex to use was then ".*aba$"

flag: **flag{h0w_m4nY_Ls_t1l_a115t4rz}**