Changed the challenge code to Python.
Solver:
```
def decrypt_flag(encrypted_flag):
runed = []
z = "\x00"

for v in encrypted_flag:
runed.append(chr(ord(v) - ord(z)))
z = runed[-1]

return ''.join(runed)

def main():
try:
with open("the", "r") as file:
encrypted_flag = file.read().strip()
flag = decrypt_flag(encrypted_flag)
print("Decrypted flag: ", flag)
except Exception as e:
print(e)
finally:
file.close()

if __name__ == "__main__":
main()

```
[Challenge source code](https://github.com/naivenom/reversing-list/tree/master/whats-a-rune)