ruby, 28 bytes

Result

WA

Duration

902ms

Code [DL]

loop{$><<gets[/(.)\\1 | ./]}

stdin

374 344
422 118
799 688
865 362
128 882
899 195
199 867
155 952
879 742
691 996
123 723
393 674
516 618
817 613
875 118
433 345
896 967
475 551
156 891
631 312
313 154
313 934
659 552
791 474
429 944
299 996
677 992
533 347
677 772
137 664
584 424
753 352

stdout

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

stderr

/volume/CODE:1:in `block in <main>': undefined method `[]' for nil:NilClass (NoMethodError)
	from /volume/CODE:1:in `loop'
	from /volume/CODE:1:in `<main>'

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffc8ee9b170 /* 9 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x55caa9a90d40 /* 9 vars */) = 0
12    execve("/usr/local/ruby-2.7.1/bin/ruby", ["/usr/local/ruby-2.7.1/bin/ruby", "/volume/CODE"], 0x55caa9a90d60 /* 9 vars */) = 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} ---
12    +++ exited with 1 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=1, si_utime=6, si_stime=2} ---
10    +++ exited with 1 +++