package yukicoder;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String roma = sc.nextLine();
		roma = sc.nextLine();
		int total = 0;
		String[] spl = roma.split(" ");
		for(int i = 0 ; i < spl.length ; i++){
			int subTotal = 0;
			for(int j = 0 ; j < spl[i].length() ; j++){
				int num = 0;
				switch(spl[i].charAt(j)){
				case 'I' :
					num = 1;
					break;
				case 'V' :
					num = 5;
					break;
				case 'X' :
					num = 10;
					break;
				case 'L' :
					num = 50;
					break;
				case 'C' :
					num = 100;
					break;
				case 'D' :
					num = 500;
					break;
				case 'M' :
					num = 1000;
					break;
					
				}
				if(num > subTotal && subTotal !=0){
					total += num - subTotal;
					subTotal = 0;
				}else{
					total += subTotal;
					subTotal = num;
				}
			}
			total += subTotal;
		}
		int[] numArray = {1000,900,500,400,100,90,50,40,10,9,5,4,1};
		String[] romaArray = {"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};
		int work = total;
		String disp = "";
		for(int i = 0 ; i < numArray.length ; i++){
			int work2 = work/numArray[i];
			for(int j = 0 ; j < work2 ; j++){
				disp+=romaArray[i];
			}
			work %= numArray[i];
		}
		if(total <= 3999){
			System.out.println(disp);
		}else{
			System.out.println("ERROR");
		}
	}

}