vim, 27 bytes

Result

AC

Duration

899ms

Code [DL]

:%s/\v.*(.)(\1| )..*/\1/
ZZ

Disassembly

:%s/\v.*(.)(\1| )..*/\1/<NL>ZZ

stdin

899 976
157 638
435 334
882 578
657 736
662 766
585 824
311 855
347 447
733 635
566 223
355 286
469 964
922 424
762 223
797 758
865 446
824 428
698 176
334 737
116 565
987 776
344 456
917 559
744 223
859 598
612 264
457 571
569 596
988 884
986 841
499 998

stdout

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

stderr

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffd8ab3ace0 /* 9 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x55c8d7215d00 /* 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("/usr/bin/vim", ["/usr/bin/vim", "-N", "-u", "NONE", "-i", "NONE", "-s", "/volume/CODE", "/tmp/out"], 0x55c8d77a8288 /* 10 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} ---
13    execve("/bin/cat", ["cat", "/tmp/out"], 0x55c8d7215c98 /* 9 vars */) = 0
13    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=13, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
14    execve("/bin/rm", ["rm", "/tmp/out"], 0x55c8d7215c98 /* 9 vars */) = 0
14    +++ exited with 0 +++
10    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
10    +++ exited with 0 +++