goruby, 14 bytes

Result

AC

Code [DL]

pts$<.ch.so*''

stdin

2112589797320084792738782899969732393963604099020691017750636754989300581868653350194584406578365327

stdout

0000000000001111112222222233333333333344444455555555566666666667777777777788888888888999999999999999

stderr

<internal:golf_prelude>:14: warning: ARGF#chars is deprecated; use #each_char instead

strace