wren, 86 bytes

Result

AC

Duration

734ms

Code [DL]

import"io"for Stdin
while(1){
var s=Stdin.readLine()
System.print(s[s[1]!=s[2]?4:2])
}

stdin

617 115
929 855
294 396
166 749
199 896
158 865
733 286
588 885
819 112
488 887
952 255
724 243
677 729
586 865
322 251
521 169
711 772
174 659
118 885
587 584
235 443
219 281
184 852
757 756
258 572
747 775
281 331
771 523
722 822
616 465
471 911
233 441

stdout

1
8
3
6
9
8
3
8
1
8
2
2
7
8
2
1
1
6
8
5
4
2
8
7
5
7
3
5
2
4
9
3

stderr

Subscript out of bounds.
[/volume/CODE line 4] in (script)

strace

12    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffd811d43c0 /* 9 vars */) = 0
13    execve("/bin/cat", ["cat", "-"], 0x556c05205d30 /* 9 vars */ <unfinished ...>
14    execve("/root/wren", ["/root/wren", "/volume/CODE"], 0x556c05205d40 /* 9 vars */) = 0
13    <... execve resumed>)             = 0
13    +++ exited with 0 +++
12    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=13, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
14    +++ exited with 0 +++
12    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
12    +++ exited with 0 +++