golang, 58 bytes

Result

WA

Duration

956ms

Code [DL]

char s[9];main(){for(;gets(s);putchar(s[s[1]-s[2]?4:2]));}

stdin

472 287
189 586
133 814
569 887
322 228
668 663
826 224
598 199
277 573
274 454
634 382
522 667
843 214
751 713
515 153
826 331
161 166
211 116
147 476
835 533
355 132
269 755
471 991
544 411
797 873
282 818
662 589
773 338
799 795
344 439
346 665
366 775

stdout

stderr

can't load package: package main: 
/tmp/code.go:1:1: expected 'package', found char
/root/script: line 7: /tmp/code: not found
rm: can't remove '/tmp/code': No such file or directory

strace

11    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffcc429ce20 /* 7 vars */) = 0
12    execve("/usr/bin/realpath", ["realpath", "/volume/CODE"], 0x558e3e623d18 /* 7 vars */) = 0
12    +++ exited with 0 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
13    execve("/bin/ln", ["ln", "-sf", "/volume/CODE", "/tmp/code.go"], 0x558e3e623d38 /* 7 vars */) = 0
13    +++ exited with 0 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=13, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
14    execve("/usr/bin/go", ["/usr/bin/go", "build", "-o", "/tmp/code", "/tmp/code.go"], 0x558e3f6fc028 /* 7 vars */) = 0
15    ????( <unfinished ...>
19    +++ exited with 1 +++
18    +++ exited with 1 +++
17    +++ exited with 1 +++
16    +++ exited with 1 +++
15    +++ exited with 1 +++
14    +++ exited with 1 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14, si_uid=0, si_status=1, si_utime=0, si_stime=0} ---
20    execve("/bin/cat", ["cat", "-"], 0x558e3e623d08 /* 7 vars */ <unfinished ...>
21    execve("/tmp/code", ["/tmp/code"], 0x558e3e623cf0 /* 7 vars */) = -1 ENOENT (No such file or directory)
20    <... execve resumed>)             = 0
20    +++ exited with 0 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=20, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
21    +++ exited with 127 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=21, si_uid=0, si_status=127, si_utime=0, si_stime=0} ---
22    execve("/bin/rm", ["rm", "/tmp/code.go", "/tmp/code"], 0x558e3e623cf0 /* 7 vars */) = 0
22    +++ exited with 1 +++
11    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=22, si_uid=0, si_status=1, si_utime=0, si_stime=0} ---
11    +++ exited with 1 +++