oh, 57 bytes

Result

INVALID

Duration

903ms

Code [DL]

sed -Ee "s/.\(.\)\\1 ...\|... \(.\)../\\1\\2/" /dev/stdin

stdin

722 117
366 658
188 836
756 562
224 448
937 329
469 566
767 662
369 927
363 951
799 291
933 823
143 446
375 852
488 378
694 541
899 996
938 882
366 221
554 454
277 778
566 461
489 832
384 228
648 113
123 452
586 861
711 172
981 189
462 235
951 756
588 495

stdout

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

stderr

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffda711ecd0 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x5647e726a048 /* 7 vars */) = 0
13    execve("/usr/bin/go", ["/usr/bin/go", "env", "GOPATH"], 0x5647e726a078 /* 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} ---
14    ????( <unfinished ...>
15    +++ exited with 0 +++
16    +++ exited with 0 +++
18    +++ exited with 0 +++
17    +++ exited with 0 +++
14    +++ exited with 0 +++
13    +++ exited with 0 +++
12    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=13, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
12    execve("/root/go/bin/oh", ["/root/go/bin/oh", "/volume/CODE"], 0x5647e726a068 /* 7 vars */) = 0
25    execve("/bin/sed", ["sed", "-Ee", "s/.(.)\\1 ...|... (.)../\\1\\2/", "/dev/stdin"], 0xc000090be0 /* 8 vars */) = 0
25    +++ exited with 0 +++
12    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=25, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
24    +++ exited with 0 +++
23    +++ exited with 0 +++
22    +++ exited with 0 +++
21    +++ exited with 0 +++
20    +++ exited with 0 +++
19    +++ exited with 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=3, si_stime=5} ---
10    +++ exited with 0 +++