#include <stdio.h>
int main( void ) {
const char* s = "MCDXLIV";
int x = 0; // result
int j,m=0; // max used digit
const char* p=s, *q; while(*p) ++p;
for( --p; p>=s; p-- ) for( q="IVXLCDM",j=0; *q; q++,j++ ) if( *p==*q )
x += ((j>=m)?m=j,1:-1) * (1+j%4/2*9) * (1+j/4*99) * (1+j%2*4);
printf( "s=%s x=%i\n", s, x );
}