%h=@@=M1000CM900D500CD400C100XC90L50XL40X10IX9V5IV4I1=~/\d+|\D+/g;<>;()=<>=~/.+(??{$s+=$x=$h{$&};!$x})/g;print+($_)=grep$h{$_}&&$s>=$h{$_},@@while$s<4e3?$s-=$h{$_}:!print"ERROR"