lua, 73 bytes

Result

AC

Duration

982ms

Code [DL]

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

stdin

217 318
897 339
736 674
241 713
313 775
479 775
659 992
399 793
319 322
277 778
433 114
824 947
877 788
722 218
496 495
688 762
982 826
196 262
829 921
766 667
713 872
477 172
522 952
399 665
985 996
354 544
448 442
548 422
817 779
598 971
173 373
547 757

stdout

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

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

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7fff612a7cb0 /* 7 vars */) = 0
12    execve("/usr/bin/lua5.3", ["/usr/bin/lua5.3", "/volume/CODE"], 0x5571c15efd40 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x5571c15efd30 /* 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 +++