function s(r,d){return gsub(r,_)*d}
$0=s("IV",4)+s("XL",40)+s("CD",400)+s("IX",9)+s("XC",90)+s("CM",900)+s("I",1)+s("X",10)+s("C",100)+s("V",5)+s("L",50)+s("D",500)+s("M",1000)
Note that non-ascii characters in the above source code will be escaped (such as \x9f).