vim, 26 bytes

Result

AC

Code [DL]

:s/\(.\)/\1\r/g|sor|%j!
ZZ

Disassembly

:s/\(.\)/\1\r/g|sor|%j!<NL>ZZ

stdin

1220596270668896756194441187750070879492477450007192272572121116918020694001693324968097200464079329

stdout

0000000000000000111111111112222222222222333444444444455555666666666677777777777778888889999999999999

stderr

strace