import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		int n = sc.nextInt();
		String[] a = {"IV","IX","XL","XC","CD","CM"};
		String[] b = {"IIII","VIIII","XXXX","LXXXX","CCCC","DCCCC"};
		StringBuilder sb = new StringBuilder();
		for (int i=0; i<n; i++) {
			String temp = sc.next();
			for (int j=0; j<6; j++) {
				temp = temp.replaceAll(a[j],b[j]);
			}
			sb.append(temp);
		}
		
		int total = 0;
		int[] number = {1000,900,500,400,100,90,50,40,10,9,5,4,1};
		String[] roma = {"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};
		for (int i=0; i<sb.length(); i++) {
			for (int j=0; j<13; j++) {
				if (sb.substring(i,i+1).equals(roma[j])) {total += number[j];}
			}
		}
		
		if (total > 3999) {System.out.println("ERROR");}
		else {
			StringBuilder ans = new StringBuilder();
			for (int i=0; i<13; i++) {
				int ii = total/number[i];
				for (int j=0; j<ii; j++) {
					ans.append(roma[i]);
				}
				total = total%number[i];
			}
			System.out.println(ans);
		}
	}
}