using System;

namespace No._518
{
    class Program
    {
        static void Main(string[] args)
        {
            int N = int.Parse(Console.ReadLine());
            string[] roma = Console.ReadLine().Split();
            Program program = new Program();
            int sum = 0;

            for (int i = 0; i < N; i++)
            {
                sum += program.CharToNum(roma[i].ToCharArray());
            }

            string ans = program.NumToChar(sum);

            Console.WriteLine(ans);
        }

        public int CharToNum(char[] roma)
        {
            int result = 0;

            Array.Reverse(roma);

            for (int i = 0; i < roma.Length; i++)
            {
                switch (roma[i])
                {
                    case 'M':
                        result += 1000;
                        break;

                    case 'D':
                        result += 500;
                        break;

                    case 'C':
                        if (i != 0)
                        {
                            if (roma[i - 1] == 'M' || roma[i - 1] == 'D')
                            {
                                result -= 100;
                                break;
                            }
                        }
                        result += 100;
                        break;

                    case 'L':
                        result += 50;
                        break;

                    case 'X':
                        if (i != 0)
                        {
                            if (roma[i - 1] == 'L' || roma[i - 1] == 'C')
                            {
                                result -= 10;
                                break;
                            }
                        }
                        result += 10;
                        break;

                    case 'V':
                        result += 5;
                        break;

                    case 'I':
                        if (i != 0)
                        {
                            if (roma[i - 1] == 'V' || roma[i - 1] == 'X')
                            {
                                result -= 1;
                                break;
                            }
                        }
                        result += 1;
                        break;
                }
            }

            return result;
        }

        public string NumToChar(int number)
        {
            if (number > 3999)
            {
                return "ERROR";
            }

            string result = "";

            if (number >= 1000)
            {
                int n = number / 1000;
                number %= 1000;

                while (n > 0)
                {
                    result += "M";
                    n--;
                }
            }

            if (number >= 100)
            {
                int n = number / 100;
                number %= 100;

                if (n == 9)
                {
                    result += "CM";
                    n -= 9;
                }
                else if (8 >= n && n >= 5)
                {
                    result += "D";
                    n -= 5;
                }
                else if (n == 4)
                {
                    result += "CD";
                    n -= 4;
                }

                while (n > 0)
                {
                    result += "C";
                    n--;
                }
            }

            if (number >= 10)
            {
                int n = number / 10;
                number %= 10;

                if (n == 9)
                {
                    result += "XC";
                    n -= 9;
                }
                else if (8 >= n && n >= 5)
                {
                    result += "L";
                    n -= 5;
                }
                else if (n == 4)
                {
                    result += "XL";
                    n -= 4;
                }

                while (n > 0)
                {
                    result += "X";
                    n--;
                }
            }

            if (number >= 1)
            {
                if (number == 9)
                {
                    result += "IX";
                    number -= 9;
                }
                else if (8 >= number && number >= 5)
                {
                    result += "V";
                    number -= 5;
                }
                else if (number == 4)
                {
                    result += "IV";
                    number -= 4;
                }

                while (number > 0)
                {
                    result += "I";
                    number--;
                }
            }

            return result;
        }
    }
}