#include "iostream"
#include <string>
#include <list>

using namespace std;

void print(int x, char a);

int main()
{
	char alavia[8] = "MDCLXVI";
	string change;
	int S = 0, sum = 0, Asum = 0, V5 = 0, X10 = 0, L50 = 0, C100 = 0, D500 = 0, M1000 = 0;
	cin >> S;
	for (int i = 0; i < S; i++) {
		cin >> change;
		int m = change.size();
		for (int j = 0; j < m; j++) {
			if (change[j] == 'I')
				sum += 1;
			else if (change[j] == 'V')
				sum += 5;
			else if (change[j] == 'X')
				sum += 10;
			else if (change[j] == 'L')
				sum += 50;
			else if (change[j] == 'C')
				sum += 100;
			else if (change[j] == 'D')
				sum += 500;
			else
				sum += 1000;
		}
		if (sum > 3999) {
			cout << "ERROR";
			return 0;
		}
		else {
			Asum += sum;
			sum = 0;
		}

	}
	if (Asum > 3999) {
		cout << "ERROR";
		return 0;
	}

	else {
		if (Asum > 999) {
			M1000 = Asum / 1000;
			print(M1000, alavia[0]);
			Asum = Asum % 1000;
		}
		if(Asum > 499) {
			D500 = Asum / 500;
			print(D500, alavia[1]);
			Asum = Asum % 500;
		}
		if (Asum > 99) {
			C100 = Asum / 100;
			print(C100, alavia[2]);
			Asum = Asum % 100;
		}
		if (Asum > 49) {
			L50 = Asum / 50;
			print(L50, alavia[3]);
			Asum = Asum % 50;
		}
		if (Asum > 9) {
			X10 = Asum / 10;
			print(X10, alavia[4]);
			Asum = Asum % 10;
		}
		if (Asum > 4) {
			V5 = Asum / 5;
			print(V5, alavia[5]);
			Asum = Asum % 5;
		}
		if (Asum > 0) {
			print(Asum, alavia[6]);
		}
		else {
		}
	}
	

	
    return 0;
}

void print(int x, char a)
{
	for (int i = 0; i < x; i++)
		cout << a;
}