#include <iostream>
#include <string>
#include <map>
using namespace std;

map<char,int> mp;

int to_int(string s){
	int prev = 0,sum = 0;
	for(int i = s.length() - 1;i >= 0;i--){
		int add = mp[s[i]];
		if(add < prev) sum -= add;
		else sum += add;
		prev = add;
	}
	return sum;
}

string to_rome(int n){
	string s;
	int num[] = {1000,500,100,50,10,5,1};
	char c[] = {'M','D','C','L','X','V','I'};
	string chg[] = {"DCCCC","CCCC","LXXXX","XXXX","VIIII","IIII"};
	string to[] = {"CM   ","CD  ","XC   ","XL  ","IX   ","IV  "};
	for(int i = 0;i < 7;i++){
		for(int j = 0;j < n / num[i];j++) s += c[i];
		n %= num[i];
	}
	for(int i = 0;i < 6;i++){
		for(int j = 0;j < (int)s.length() - (int)chg[i].length() + 1;j++){
			if(s.substr(j,chg[i].length()) == chg[i]){
				for(int k = 0;k < chg[i].length();k++) s[j + k] = to[i][k];
			}
		}
	}
	string t;
	for(int i = 0;i < s.length();i++){
		if(s[i] != ' ') t += s[i];
	}
	return t;
}

int main(){
	int n;
	cin >> n;
	mp['I'] = 1;
	mp['V'] = 5;
	mp['X'] = 10;
	mp['L'] = 50;
	mp['C'] = 100;
	mp['D'] = 500;
	mp['M'] = 1000;
	int ans = 0;
	for(int i = 0;i < n;i++){
		string s;
		cin >> s;
		ans += to_int(s);
	}
	if(ans >= 4000) cout << "ERROR" << endl;
	else cout << to_rome(ans) << endl;
	return 0;
}