wren, 88 bytes

Result

AC

Duration

742ms

Code [DL]

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

stdin

515 643
861 321
192 259
566 447
686 854
512 213
488 683
988 896
829 895
855 552
576 278
641 335
155 595
741 138
488 624
977 873
315 961
412 113
433 174
977 887
639 771
986 865
561 266
358 855
264 447
741 817
872 228
446 467
211 113
265 698
227 227
796 337

stdout

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

stderr

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

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7fff332e82c0 /* 9 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x557d2e0fbd30 /* 9 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    execve("/root/wren", ["/root/wren", "/volume/CODE"], 0x557d2e0fbd40 /* 9 vars */) = 0
12    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=12, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
10    +++ exited with 0 +++