#include <bits/stdc++.h>

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define RFOR(i, a, b) for (int i = (b)-1; i >= (a); i--)
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, n) for (int i = 1; i <= (n); i++)
#define rrep(i, n) for (int i = (n)-1; i >= 0; i--)

#define pb push_back
#define mp make_pair
#define fst first
#define snd second
#define show(x) cout << #x << " = " << x << endl
#define chmin(x, y) x = min(x, y)
#define chmax(x, y) x = max(x, y)
#define pii pair<int, int>
#define vi vector<int>

using namespace std;
template <class S, class T>
ostream& operator<<(ostream& o, const pair<S, T>& p)
{
    return o << "(" << p.first << "," << p.second << ")";
}
template <class T>
ostream& operator<<(ostream& o, const vector<T>& vc)
{
    o << "sz = " << vc.size() << endl
      << "[";
    for (const T& v : vc)
        o << v << ",";
    o << "]";
    return o;
}
using ll = long long;
constexpr ll MOD = 1000000007;
struct RomanRadix {
    int digit;
    char roman;
    char romanNext;
    //	Radix(int d, char r, char rn):digit(d),roman(r),romanNext(rn){}
};

const int ROMAN_MAX_VALUE = 3999;
const int ROMAN_MIN_VALUE = 1;
const char RomanChars[] = "IVXLCDMivxlcdm";

class Roman
{
private:
    static bool isRomanString(const string& rstr)
    {
        return rstr.find_first_not_of(RomanChars) == string::npos;
    }
    static int rtoi_aux(const char ch)
    {
        static const char romans[] = "IVXLCDM";
        static const int digit[] = {1, 5, 10, 50, 100, 500, 1000};
        for (int i = 0; romans[i]; ++i)
            if (toupper(ch) == romans[i])
                return digit[i];
        return -1;
    }
    static int rtoi(const string& rstr)
    {
        int v, wk = 0;

        for (const char* p = rstr.c_str(); *p; ++p) {
            if ((v = rtoi_aux(*p)) < rtoi_aux(*(p + 1)))
                wk -= v;
            else
                wk += v;
        }
        return wk;
    }

    int num;
    string itor() const;

public:
    Roman() : num(0) {}
    Roman(const int n);
    Roman(const string& r);
    int as_int() const { return num; }
    string as_str() const { return itor(); }
    friend Roman operator+(const Roman& a, const Roman& b)
    {
        int n = a.num + b.num;
        if (n > ROMAN_MAX_VALUE)
            throw std::overflow_error("overflow");
        return Roman(n);
    }
    friend Roman operator-(const Roman& a, const Roman& b)
    {
        int n = a.num - b.num;
        if (n < ROMAN_MIN_VALUE)
            throw std::underflow_error("underflow");
        return Roman(n);
    }
};
Roman::Roman(const int n) : num(n)
{
    if (num < 1 || 3999 < num)
        throw out_of_range("value need 1 - 3999");
};

Roman::Roman(const string& r)
{
    if (!isRomanString(r))
        throw invalid_argument("invalid character use");

    num = rtoi(r);
    if (num < 1 || 3999 < num)
        throw out_of_range("value need 1 - 3999");
};

string Roman::itor() const
{
    static RomanRadix table[] = {
        {1000, 'M', '?'},
        {100, 'C', 'D'},
        {10, 'X', 'L'},
        {1, 'I', 'V'}};

    const int tableSize = sizeof(table) / sizeof(RomanRadix);
    char buff[16];  //max size: 15
    char* p = buff;

    for (int i = 0, wk = num; i < tableSize; ++i) {
        int n = wk / table[i].digit;
        if (1 <= n && n <= 3) {
            for (int j = 0; j < n; ++j)
                *p++ = table[i].roman;
        } else if (n == 4) {
            *p++ = table[i].roman;
            *p++ = table[i].romanNext;
        } else if (n == 5) {
            *p++ = table[i].romanNext;
        } else if (6 <= n && n <= 8) {
            *p++ = table[i].romanNext;
            for (int j = 0; j < n - 5; ++j)
                *p++ = table[i].roman;
        } else if (n == 9) {
            *p++ = table[i].roman;
            *p++ = table[i - 1].roman;
        }
        wk -= n * table[i].digit;
    }
    *p = '\0';

    return string(buff);
};


ostream& operator<<(ostream& os, const Roman& r)
{
    return os << r.as_str();
}

istream& operator>>(istream& is, Roman& r)
{
    string rstr;
    is >> rstr;
    try {
        r = Roman(rstr);
    } catch (invalid_argument& e) {
        cerr << e.what() << endl;
        is.clear(ios_base::failbit);
    }
    return is;
}

std::ostream& operator<<(std::ostream& os, const Roman& r);
std::istream& operator>>(std::istream& is, Roman& r);

int main()
{
    int N;
    cin >> N;
    int sum = 0;
    rep(i, N)
    {
        string str;
        cin >> str;
        Roman r(str);
        sum += r.as_int();
    }
    if (sum >= 4000) {
        cout << "ERROR" << endl;
        return 0;
    }
    Roman r(sum);
    cout << r.as_str() << endl;
    return 0;
}