python3, 52 bytes

Result

AC

Duration

1520ms

Code [DL]

while s:=input():print(s[2] if s[1]==s[2] else s[4])

stdin

674 978
287 787
899 393
588 886
439 636
524 241
211 113
922 273
833 392
177 564
274 382
576 779
899 772
562 669
277 497
329 112
123 276
382 525
344 332
986 852
336 615
793 533
375 883
697 577
711 918
397 791
582 225
569 466
836 667
892 237
728 979
695 959

stdout

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

stderr

Traceback (most recent call last):
  File "/volume/CODE", line 1, in <module>
    while s:=input():print(s[2] if s[1]==s[2] else s[4])
EOFError: EOF when reading a line

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffe665de6c0 /* 7 vars */) = 0
12    execve("/usr/bin/python3", ["/usr/bin/python3", "/volume/CODE"], 0x55e716f3cd50 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x55e716f3cd38 /* 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=2, si_stime=1} ---
10    +++ exited with 1 +++