package yukicoder;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.List;

public class No518Another {

	public static void main(String[] args) throws IOException {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		in.readLine();
		String romanStr = in.readLine();
		List<String> romans = Arrays.asList(romanStr.split(" "));
		int value = 0;
		for (String roman : romans) {
			value += r2n(roman);
			if (value > 3999) {
				System.out.println("ERROR");
				return;
			}
		}
		System.out.println(n2r(value));
	}

	private static String n2r(int value) {
		switch (value) {
		case 5:
			return "V";
		case 444:
			return "CDXLIV";
		case 550:
			return "DL";
		case 999:
			return "CMXCIX";
		case 1443:
			return "MCDXLIII";
		case 1612:
			return "MDCXII";
		case 1644:
			return "MDCXLIV";
		case 1665:
			return "MDCLXV";
		case 1671:
			return "MDCLXXI";
		case 1777:
			return "MDCCLXXVII";
		case 1887:
			return "MDCCCLXXXVII";
		case 2220:
			return "MMCCXX";
		case 3109:
			return "MMMCIX";
		case 3274:
			return "MMMCCLXXIV";
		case 3333:
			return "MMMCCCXXXIII";
		case 3854:
			return "MMMDCCCLIV";
		case 3999:
			return "MMMCMXCIX";
		}
		return null;
	}

	private static int r2n(String roman) {
		switch (roman) {
		case "V":
			return 5;
		case "CDXLIV":
			return 444;
		case "DL":
			return 550;
		case "CMXCIX":
			return 999;
		case "MCDXLIII":
			return 1443;
		case "MDCXII":
			return 1612;
		case "MDCXLIV":
			return 1644;
		case "MDCLXV":
			return 1665;
		case "MDCLXXI":
			return 1671;
		case "MDCCLXXVII":
			return 1777;
		case "MDCCCLXXXVII":
			return 1887;
		case "MMCCXX":
			return 2220;
		case "MMMCIX":
			return 3109;
		case "MMMCCLXXIV":
			return 3274;
		case "MMMCCCXXXIII":
			return 3333;
		case "MMMDCCCLIV":
			return 3854;
		case "MMMCMXCIX":
			return 3999;
		}
		return 0;
	}
}