ruby, 49 bytes

Result

WA

Duration

1692ms

Code [DL]

puts $<.chars.map{|c|c=c>'@'&&c<'['?'1':'0'}.join

stdin

aBCDEFgHijKlMNOpQrSTUVWXYZ

stdout

011111010010111010111111110

stderr

/volume/CODE:1: warning: ARGF#chars is deprecated; use #each_char instead

strace

10    execve("/bin/sh", ["/bin/sh", "/root/script", "/volume/CODE"], 0x7ffdf765eac0 /* 9 vars */) = 0
11    execve("/bin/cat", ["cat", "-"], 0x5595f4b75d40 /* 9 vars */) = 0
12    execve("/usr/local/ruby-2.7.1/bin/ruby", ["/usr/local/ruby-2.7.1/bin/ruby", "/volume/CODE"], 0x5595f4b75d60 /* 9 vars */ <unfinished ...>
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=5, si_stime=4} ---
10    +++ exited with 0 +++