The aliens are at it again! We've discovered that their communications are in base 512 and have transcribed them in base 10. However, it seems like they used XOR encryption twice with two different keys! We do have some information:

• This alien language consists of words delimitated by the character represented as 481
• The two keys appear to be of length 21 and 19
• The value of each character in these keys does not exceed 255
• Find these two keys for me; concatenate their ASCII encodings and wrap it in the flag format.