perl, 28 bytes

Result

WA

Duration

836ms

Code [DL]

print/(.)\1 /?$1:/ ./g for<>

stdin

411 998
833 833
855 995
788 833
394 748
537 774
949 493
588 687
313 533
477 399
327 478
993 989
334 446
879 791
826 625
114 489
154 552
657 284
758 492
345 514
311 149
267 996
639 837
698 434
544 445
159 851
847 882
412 162
453 552
127 723
511 864
644 447

stdout

1358 7 7 48 57 4 9 4 7 6 4 5 2 4 51 9 8 44 8 8 1 5 714

stderr

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffc8558c550 /* 7 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x5561ac444d30 /* 7 vars */ <unfinished ...>
12    execve("/usr/bin/perl", ["/usr/bin/perl", "/volume/CODE"], 0x5561ac444d40 /* 7 vars */ <unfinished ...>
11    <... execve resumed>)             = 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 resumed>)             = 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} ---
10    +++ exited with 0 +++