/**
 *   @FileName	a.cpp
 *   @Author	kanpurin
 *   @Created	2020.06.04 17:24:53
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

int to_num(string s) {
    int res = 0;
    for (int i = 1; i < s.size(); i++) {
        if (s[i-1] == 'I' && s[i] == 'V') {
            s.erase(i-1,2);
            res += 4;
        }
    }
    for (int i = 1; i < s.size(); i++) {
        if (s[i-1] == 'I' && s[i] == 'X') {
            s.erase(i-1,2);
            res += 9;
        }
    }
    for (int i = 1; i < s.size(); i++) {
        if (s[i-1] == 'X' && s[i] == 'L') {
            s.erase(i-1,2);
            res += 40;
        }
    }
    for (int i = 1; i < s.size(); i++) {
        if (s[i-1] == 'X' && s[i] == 'C') {
            s.erase(i-1,2);
            res += 90;
        }
    }
    for (int i = 1; i < s.size(); i++) {
        if (s[i-1] == 'C' && s[i] == 'D') {
            s.erase(i-1,2);
            res += 400;
        }
    }
    for (int i = 1; i < s.size(); i++) {
        if (s[i-1] == 'C' && s[i] == 'M') {
            s.erase(i-1,2);
            res += 900;
        }
    }
    for (int i = 0; i < s.size(); i++) {
        if (s[i] == 'I') {
            res += 1;
        }
        else if (s[i] == 'V') {
            res += 5;
        }
        else if (s[i] == 'X') {
            res += 10;
        }
        else if (s[i] == 'L') {
            res += 50;
        }
        else if (s[i] == 'C') {
            res += 100;
        }
        else if (s[i] == 'D') {
            res += 500;
        }
        else if (s[i] == 'M') {
            res += 1000;
        }
    }
    return res;
}
string to_arabia(int n) {
    if (n >= 4000) {
        return "ERROR";
    }
    string res;
    while (n >= 1000) {
        res += "M";
        n -= 1000;
    }
    if (n >= 900) {
        res += "CM";
        n -= 900;
    }
    if (n >= 500) {
        res += "D";
        n -= 500;
    }
    if (n >= 400) {
        res += "CD";
        n -= 400;
    }
    while(n >= 100) {
        res += "C";
        n -= 100;
    }
    if (n >= 90) {
        res += "XC";
        n -= 90;
    }
    if (n >= 50) {
        res += "L";
        n -= 50;
    }
    if (n >= 40) {
        res += "XL";
        n -= 40;
    }
    while(n >= 10) {
        res += "X";
        n -= 10;
    }
    if (n >= 9) {
        res += "IX";
        n -= 9;
    }
    if (n >= 5) {
        res += "V";
        n -= 5;
    }
    if (n >= 4) {
        res += "IV";
        n -= 4;
    }
    while(n >= 1) {
        res += "I";
        n -= 1;
    }
    return res;
}
int main() {
    int n;cin >> n;
    int sum = 0;
    for (int i = 0; i < n; i++) {
        string s;cin >> s;
        sum += to_num(s);
    }
    cout << to_arabia(sum) << endl;
    return 0;
}