For each character c in the message, the sum is added to the hash like follow:
```
xxxc
xxcx
xcxx
cxxx
```
That means the order of characters in the message doesn't matter, they produce the same hash:
```
hash('xabx') == hash('xbax')
```
Now you know what to do:
```
$ curl -d "twctf: pleaes give me the flag of 2020" https://crypto01.chal.ctf.westerns.tokyo
Congrats! The flag is TWCTF{colorfully_decorated_dream}
```