python3, 47 bytes

Result

AC

Duration

1051ms

Code [DL]

while s:=input():print([s[2],s[4]][s[1]!=s[2]])

stdin

925 212
879 698
128 882
133 833
199 412
922 244
961 461
535 247
211 911
611 116
237 372
263 349
984 987
415 965
515 163
388 884
981 882
911 441
399 664
565 446
384 265
759 956
895 558
422 181
933 384
498 718
461 512
263 631
279 779
378 896
195 599
471 221

stdout

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

stderr

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

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7fff1c750db0 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x55d2f3e74d38 /* 7 vars */) = 0
12    execve("/usr/bin/python3", ["/usr/bin/python3", "/volume/CODE"], 0x55d2f3e74d50 /* 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 +++