#include <iostream>
#include <string>
#include <vector>
using namespace std;

vector<int> range {1000,500,100,50,10,5,1};

int toNum(char rouma)
{
    switch(rouma)
    {
        case 'I': return 1;
        case 'V': return 5;
        case 'X': return 10;
        case 'L': return 50;
        case 'C': return 100;
        case 'D': return 500;
        case 'M': return 1000;
    }
    throw;
}

inline int toNum(string rouma)
{
    int ret = 0;
    int last = 0;
    for(char c : rouma)
    {
        int curr = toNum(c);
        ret += curr;
        if (curr > last)
        {
            ret -= last*2;
        }
        last = curr;
    }
    return ret;
}

inline char getRouma(int num)
{
    switch(num)
    {
        case 1   : return 'I';
        case 5   : return 'V';
        case 10  : return 'X';
        case 50  : return 'L';
        case 100 : return 'C';
        case 500 : return 'D';
        case 1000: return 'M';
    }
    throw;
}

inline char getNext(int num)
{
    switch(num)
    {
        case 1   : return 'V';
        case 5   : return 'X';
        case 10  : return 'L';
        case 50  : return 'C';
        case 100 : return 'D';
        case 500 : return 'M';
    }
    throw;
}

string toRouma(int num)
{
    if (num > 3999) return "ERROR";
    vector<int> niseMap(1024);
    for(int i : range)
    {
        while(num >= i)
        {
            ++niseMap[i];
            num -= i;
        }
    }
    string ret;
    for(int i : range)
    {
        int cnt = niseMap[i];
        if (cnt != 0)
        {
            if (cnt == 4)
            {
                if (*ret.rbegin() == getNext(i))
                {
                    //ret = "V"; i = 1; cnt = 4;
                    //VIV => IX
                    ret.pop_back();
                    ret += getRouma(i);
                    ret += getNext(toNum(getNext(i)));
                }
                else
                {
                    //IIII => IV;
                    ret += getRouma(i);
                    ret += getNext(i);
                }
            }
            else
            {
                ret += string(cnt, getRouma(i));
            }
        }
    }
    return ret;
}

int main()
{
    int n;
    cin >> n;
    vector<string> arr(n);
    int sum = 0;
    for(int i = 0; i < n; ++i)
    {
        cin >> arr[i];
        int num = toNum(arr[i]);
        sum += num;
        //cout << num << endl;
    }
    //cout << sum << endl;
    cout << toRouma(sum) << endl;
}