lua, 72 bytes

Result

WA

Duration

902ms

Code [DL]

::x::a,b=io.read("*n","*n")c=a%10print(c==a/10%10 and c or b//100)goto x

stdin

342 448
956 794
154 756
178 951
288 869
511 117
882 824
589 989
228 862
637 276
697 498
471 112
599 998
466 369
216 373
199 839
517 337
334 362
144 885
728 788
877 758
754 457
875 494
668 884
655 155
969 915
299 886
742 423
923 226
722 578
626 276
676 443

stdout

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

stderr

/usr/bin/lua5.3: /volume/CODE:1: attempt to perform arithmetic on a nil value (global 'a')
stack traceback:
	/volume/CODE:1: in main chunk
	[C]: in ?

strace

14    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffdf4d15a20 /* 7 vars */) = 0
15    execve("/bin/cat", ["cat", "-"], 0x55cc4a8c5d30 /* 7 vars */ <unfinished ...>
16    execve("/usr/bin/lua5.3", ["/usr/bin/lua5.3", "/volume/CODE"], 0x55cc4a8c5d40 /* 7 vars */ <unfinished ...>
15    <... execve resumed>)             = 0
15    +++ exited with 0 +++
14    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=15, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
16    <... execve resumed>)             = 0
16    +++ exited with 1 +++
14    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=16, si_uid=0, si_status=1, si_utime=0, si_stime=0} ---
14    +++ exited with 1 +++