lua, 127 bytes

Result

WA

Duration

1032ms

Code [DL]

for i = 0, 31, 1 do
a,b=io.read("*n","*n")
if a%10==(a%100-a%10)/10
then io.write (a%10)
else io.write (b%100-b%10)/100
end
end

stdin

642 218
266 264
913 427
621 421
177 992
439 322
966 763
755 575
517 712
571 717
479 231
121 117
886 285
799 265
112 123
292 993
599 772
388 885
624 116
265 534
671 479
733 334
755 578
191 196
246 669
794 117
765 834
183 889
825 269
275 654
174 148
177 939

stdout

stderr

/usr/bin/lua5.3: /volume/CODE:5: unexpected symbol near '/'

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7fff45e1f210 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x5579130cbd30 /* 7 vars */ <unfinished ...>
12    execve("/usr/bin/lua5.3", ["/usr/bin/lua5.3", "/volume/CODE"], 0x5579130cbd40 /* 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} ---
12    +++ exited with 1 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=1, si_utime=0, si_stime=0} ---
10    +++ exited with 1 +++