#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdlib.h>
int main(){
char s[1000]={},S[1000]={};
memset(s, '\0', strlen(s));
memset(S, '\0', strlen(s));
long long int i=0 , n=0 , N=0 , A=0 ;
//羅馬數字轉數字
while(scanf("%s",s)){
if(s[0]=='#'){
break;
}
A=0;
i=0;
n=0;
N=0;
scanf("%s",S);
for(i=0;i<strlen(s);i++){
if(i<strlen(s)-1){
if(s[i]=='I'&&s[i+1]=='V'){
n=n-2;
}
if(s[i]=='X'&&s[i+1]=='C'){
n=n-20;
}
if(s[i]=='I'&&s[i+1]=='X'){
n=n-2;
}
if(s[i]=='X'&&s[i+1]=='L'){
n=n-20;
}
if(s[i]=='C'&&s[i+1]=='D'){
n=n-200;
}
if(s[i]=='C'&&s[i+1]=='M'){
n=n-200;
}
}
if(s[i]=='I'){
n=n+1;
}
else if(s[i]=='V'){
n=n+5;
}
else if(s[i]=='X'){
n=n+10;
}
else if(s[i]=='L'){
n=n+50;
}
else if(s[i]=='C'){
n=n+100;
}
else if(s[i]=='D'){
n=n+500;
}
else if(s[i]=='M'){
n=n+1000;
}
}
for(i=0;i<strlen(S);i++){
if(i<strlen(S)-1){
if(S[i]=='I'&&S[i+1]=='V'){
N=N-2;
}
if(S[i]=='X'&&S[i+1]=='C'){
N=N-20;
}
if(S[i]=='I'&&S[i+1]=='X'){
N=N-2;
}
if(S[i]=='X'&&S[i+1]=='L'){
N=N-20;
}
if(S[i]=='C'&&S[i+1]=='D'){
N=N-200;
}
if(S[i]=='C'&&S[i+1]=='M'){
N=N-200;
}
}
if(S[i]=='I'){
N=N+1;
}
else if(S[i]=='V'){
N=N+5;
}
else if(S[i]=='X'){
N=N+10;
}
else if(S[i]=='L'){
N=N+50;
}
else if(S[i]=='C'){
N=N+100;
}
else if(S[i]=='D'){
N=N+500;
}
else if(S[i]=='M'){
N=N+1000;
}
}
i=0;
if(N>n){
A=N-n;
}
if(N<n){
A=n-N;
}
if(N==n){
printf("ZERO");
}
//數字轉羅馬數字
while(A>=1000){
if(A/1000>0){
printf("M");
A=A-1000;
}
}
while(A>=900){
if(A/900>0){
printf("CM");
A=A-900;
}
}
while(A>=500){
if(A/500>0){
printf("D");
A=A-500;
}
}
while(A>=400){
if(A/400>0){
printf("CD");
A=A-400;
}
}
while(A>=100){
if(A/100>0){
printf("C");
A=A-100;
}
}
while(A>=90){
if(A/90>0){
printf("XC");
A=A-90;
}
}
while(A>=50){
if(A/50>0){
printf("L");
A=A-50;
}
}
while(A>=40){
if(A/40>0){
printf("XL");
A=A-40;
}
}
while(A>=10){
if(A/10>0){
printf("X");
A=A-10;
}
}
while(A>=9){
if(A/9>0){
printf("IX");
A=A-9;
}
}
while(A>=5){
if(A/5>0){
printf("V");
A=A-5;
}
}
while(A>=4){
if(A/4>0){
printf("IV");
A=A-4;
}
}
while(A>=1){
if(A/1>0){
printf("I");
A=A-1;
}
}
memset(s, '\0', strlen(s));
memset(S, '\0', strlen(s));
printf("\n");
}
return 0;
}