bash-pure, 71 bytes

Result

WA

Code [DL]

while[read -n1 C]{++a[C]};for((;i++<10;)){for((j=a[i];j--;)){o+=$i}};$o

stdin

5440508869094540199837555622775066104133266176022779717016225803097298774682523917575754046665723931

stdout

stderr

/bin/bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8)
/code.bash: line 1: syntax error near unexpected token `{for'
/code.bash: line 1: `while[read -n1 C]{++a[C]};for((;i++<10;)){for((j=a[i];j--;)){o+=$i}};$o'

strace