bash-pure, 50 bytes

Result

WA

Code [DL]

f()(read -n1 c&&a[c]+=$c&&f);f
IFS=;echo "${a[*]}"

stdin

9024040731892729613422876562042895367272680102618412442684998625597935413539712474671683829537870474

stdout

stderr

/bin/bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8)

strace