#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ul = unsigned long;
using ull = unsigned long long;

string encode(string s)
{
	vector<string> vs = { "IV","IX","XL","XC","CD","CM" };
	vector<string> vd = { "IIII","VIIII","XXXX","XXXXL","CCCC","CCCCD" };

	string ss{ s };
	for (unsigned i = 0; i < vs.size(); ++i)
	{
		size_t pos = 0;
		while ((pos = ss.find(vs[i], pos)) != string::npos)
		{
			ss.replace(pos, vs[i].length(), vd[i]);
			pos += vd[i].length();
		}
	}
	return ss;
}

string decode(string s)
{
	vector<string> vs = { "CM","CD","XC","XL","IX","IV" };
	vector<string> vd = { "CCCCD","CCCC","XXXXL","XXXX","VIIII","IIII" };

	string ss{ s };
	for (unsigned i = 0; i < vs.size(); ++i)
	{
		size_t pos = 0;
		while ((pos = ss.find(vd[i], pos)) != string::npos)
		{
			ss.replace(pos, vd[i].length(), vs[i]);
			pos += vs[i].length();
		}
	}
	return ss;
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int n;
	cin >> n;

	vector<string> r(n);
	for (auto&& it : r)
	{
		string s;
		cin >> s;
		it = encode(s);
	}

	vector<int> v = { 1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1 };
	map<char, int> me = { {'I',1},{'V',5},{'X',10},{'L',50},{'C',100},{'D',500},{'M',1000} };
	map<int, string> md = { {1,"I"},{4,"IV"},{5,"V"},{9,"IX"},{10,"X"},{40,"XL"},{50,"L"},{90,"XC"},{100,"C"},{400,"CD"},{500,"D"},{900,"CM"},{1000,"M"} };

	int sum{ 0 };
	for (const auto& it : r)
	{
		for (const auto& it2 : it)
			sum += me[it2];
	}

	string res;
	if (sum > 3999)
		res = "ERROR";
	else
	{
		for (const auto& it : v)
		{
			int d = sum / it;
			if (d)
			{
				for (int i = 0; i < d; ++i)
					res += md[it];
				sum -= it * d;
			}
		}
		res = decode(res);
	}
	cout << res << "\n";

	return 0;
}