# Problem
The problem is to find a pattern and solve it, the length is `26`. This challenge was a little guessing, but nothing that you can figure out in 10 minutes.
After typing `F#{` and `A#{` I got the pattern, it returns `char(ord(input[i]) ^ ord(flag[i]))` to the user. This is a trivial problem.
# Solution script
```
from pwn import *

r = remote('142.93.113.55', 31087)

brute = ""
r.recvuntil(":")
r.sendline("start")
k = 0
while len(brute) != 26:
r.recvuntil("Input:")
r.sendline(brute+'a')
ln = r.recvline()
nxt = ln.split(':')[1][len(brute)+1]
if( nxt != '\x00' ):
brute += chr(ord('a') ^ ord(nxt))
else:
brute += 'a'
print(brute)

k.close()
```