vim, 30 bytes

Result

AC

Duration

1379ms

Code [DL]

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

Disassembly

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

stdin

733 639
133 348
638 226
411 598
524 925
397 773
962 226
431 495
286 814
447 767
856 568
612 922
771 172
731 133
746 442
477 212
386 173
654 567
332 321
866 689
833 335
413 144
655 887
788 885
716 235
599 298
437 337
715 319
653 885
166 775
382 429
821 163

stdout

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

stderr

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffeceb5ea80 /* 9 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x5634e7defd00 /* 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"], 0x5634e86e2288 /* 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"], 0x5634e7defc98 /* 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"], 0x5634e7defc98 /* 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 +++