using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;

class Program
{
    public void Proc()
    {
        int MaxLimit = 3999;

        int itemCount = int.Parse(Reader.ReadLine());
        string[] inpt = new string[itemCount];

        inpt = Reader.ReadLine().Split(' ');

        int ans = 0;
        foreach (string roman in inpt)
        {
            ans += RomanToArabic(roman);
        }
        if (ans > MaxLimit)
        {
            Console.WriteLine("ERROR");
        }
        else
        {
            Console.WriteLine(this.ArabicToRoman(ans));
        }
    }

    private int RomanToArabic(string inpt)
    {
        int idx = -1;
        int ans = 0;
        while (++idx < inpt.Length)
        {
            if (idx < inpt.Length - 1)
            {
                if (Conv(inpt[idx]) < Conv(inpt[idx+1]))
                {
                    ans += Conv(inpt[idx + 1]) - Conv(inpt[idx]);
                    idx++;
                    continue;
                }
            }
            ans += Conv(inpt[idx]);
        }
        return ans;

    }

    private string ArabicToRoman(int num)
    {
        int calc = num;

        StringBuilder ans = new StringBuilder();
        int tmp = calc / 1000;
        for (int i = 0; i < tmp; i++)
        {
            ans.Append("M");
        }
        calc = calc % 1000;
        tmp = calc / 100;
        if (tmp == 9)
        {
            ans.Append("MC");
            tmp -= 9;
        }
        if (tmp >= 5)
        {
            ans.Append("D");
            tmp -= 5;
        }
        if (tmp == 4)
        {
            ans.Append("CD");
            tmp -= 4;
        }
        for (int i = 0; i < tmp; i++)
        {
            ans.Append("C");
        }
        calc = calc % 100;
        tmp = calc / 10;
        if (tmp == 9)
        {
            ans.Append("XC");
            tmp -= 9;
        }
        if (tmp >= 5)
        {
            ans.Append("L");
            tmp -= 5;
        }
        if (tmp == 4)
        {
            ans.Append("XL");
            tmp -= 4;
        }
        for (int i = 0; i < tmp; i++)
        {
            ans.Append("X");
        }
        calc = calc % 10;
        tmp = calc;
        if (tmp == 9)
        {
            ans.Append("IX");
            tmp -= 9;
        }
        if (tmp >= 5)
        {
            ans.Append("V");
            tmp -= 5;
        }
        if (tmp == 4)
        {
            ans.Append("IV");
            tmp -= 4;
        }
        for (int i = 0; i < tmp; i++)
        {
            ans.Append("I");
        }
        return ans.ToString();
    }

    private int Conv(char c)
    {
        // I = 1、V = 5、X = 10、L = 50、C = 100、D = 500、M = 1000

        switch (c)
        {
            case 'I':
                return 1;
            case 'V':
                return 5;
            case 'X':
                return 10;
            case 'L':
                return 50;
            case 'C':
                return 100;
            case 'D':
                return 500;
            default:
                return 1000;
        }
    }




    public class Reader
    {
        public static bool IsDebug = false;
        private static String PlainInput = @"





5
IV XXI CCCXL III MMCMVI





";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
    }
    static void Main()
    {
#if DEBUG
        Reader.IsDebug = true;
#endif
        Program prg = new Program();
        prg.Proc();
    }
}