perl, 38 bytes

Result

AC

Duration

550ms

Code [DL]

for(<>){s/kyoto/K/g;s/kyo|to//g;print}

stdin

tokyokyokyokyokyotokyotokyokyototototokyototokyoto

stdout

KKKKK

stderr

strace

12    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7fff7a074c98 /* 7 vars */) = 0
14    execve("/usr/bin/perl", ["/usr/bin/perl", "/volume/CODE"], 0x7fe820fd9240 /* 7 vars */ <unfinished ...>
13    execve("/bin/cat", ["cat", "-"], 0x7fe820fd9230 /* 7 vars */ <unfinished ...>
14    <... execve resumed>)             = 0
13    <... execve resumed>)             = 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} ---
14    +++ exited with 0 +++
12    --- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=14, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
12    +++ exited with 0 +++