lua, 123 bytes

Result

WA

Duration

792ms

Code [DL]

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

stdin

833 737
525 131
641 345
734 941
782 819
733 664
477 748
361 661
813 133
486 263
573 322
459 996
766 664
926 636
548 848
477 783
247 474
884 882
322 376
622 929
233 224
623 727
644 442
796 773
547 981
145 548
747 495
322 787
945 554
475 114
322 667
321 115

stdout

stderr

/usr/bin/lua5.3: /volume/CODE:1: ',' expected near '31'

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffc399692d0 /* 7 vars */) = 0
12    execve("/usr/bin/lua5.3", ["/usr/bin/lua5.3", "/volume/CODE"], 0x55c64afd6d40 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x55c64afd6d30 /* 7 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=0, si_stime=0} ---
10    +++ exited with 1 +++