node, 83 bytes

Result

AC

Duration

794ms

Code [DL]

console.log((""+require("fs").readFileSync(0)).replace(/.+/gm,s=>s[s[1]-s[2]?4:2]))

stdin

942 226
938 937
177 446
849 541
744 413
714 151
355 134
544 993
319 977
295 154
429 772
466 638
835 358
277 842
251 599
956 242
417 177
546 679
858 558
279 778
577 179
391 412
334 449
516 378
873 155
933 331
285 588
851 158
797 122
688 883
139 221
533 432

stdout

2
9
7
5
4
1
5
4
9
1
7
6
3
7
5
2
1
6
5
7
7
4
4
3
1
3
5
1
1
8
2
3

stderr

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffd5875d850 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x5557b462ed30 /* 7 vars */ <unfinished ...>
12    execve("/usr/bin/node", ["/usr/bin/node", "/volume/CODE"], 0x5557b462ed40 /* 7 vars */ <unfinished ...>
11    <... execve resumed>)             = 0
12    <... execve resumed>)             = 0
11    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=11, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
17    +++ exited with 0 +++
15    +++ exited with 0 +++
16    +++ exited with 0 +++
14    +++ exited with 0 +++
13    +++ exited with 0 +++
18    +++ exited with 0 +++
12    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=0, si_utime=5, si_stime=1} ---
10    +++ exited with 0 +++