s/(M)|D/4x@-x5/eg,s/C4//,$\=y/LXVIC4/DCLXM/for(<>)x3;print

##</code><code>##

y/DCLXVIM /4 DCLX9/,$\=s/( )?\d/9x($&+!$1)/egfor(<>)x4;print

##</code><code>##

s/M2//,y/DCLXVIM/1MDCLX2/,$\=s/\d/2x$&x5/egfor(<>)x4;print