#include "bits/stdc++.h"
using namespace std;
#define int long long
#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 RREP(i, n) for(int i=(n-1); i>=0; i--)
#define ALL(a) (a).begin(),(a).end()
#define UNIQUE_SORT(l) sort(ALL(l)); l.erase(unique(ALL(l)), l.end());
#define CONTAIN(a, b) find(ALL(a), (b)) != (a).end()
#define array2(type, x, y) array<array<type, y>, x>
#define vector2(type) vector<vector<type> >
#define out(...) printf(__VA_ARGS__)

int dxy[] = {0, 1, 0, -1, 0};

void solve();
signed main()
{
#if DEBUG
    std::ifstream in("input.txt");
    std::cin.rdbuf(in.rdbuf());
#endif
    cin.tie(0);
    ios::sync_with_stdio(false);
    solve();
    return 0;
}

/*================================*/

int N;
string r;

std::string replaceStringAll(std::string str,
                             const std::string& replace,
                             const std::string& with) {
    if(!replace.empty()) {
        std::size_t pos = 0;
        while ((pos = str.find(replace, pos)) != std::string::npos) {
            str.replace(pos, replace.length(), with);
            pos += with.length();
        }
    }
    return str;
}

int str2int(string r) {
    r = replaceStringAll(r, "CM", "CCCCCCCCC");
    r = replaceStringAll(r, "CD", "CCCC");
    r = replaceStringAll(r, "XC", "XXXXXXXXX");
    r = replaceStringAll(r, "XL", "XXXX");
    r = replaceStringAll(r, "IX", "IIIIIIIII");
    r = replaceStringAll(r, "IV", "IIII");
    int ret = 0;
    for (char c:r) {
        switch (c) {
            case 'I': ret += 1; break;
            case 'V': ret += 5; break;
            case 'X': ret += 10; break;
            case 'L': ret += 50; break;
            case 'C': ret += 100; break;
            case 'D': ret += 500; break;
            case 'M': ret += 1000; break;
        }
    }
    return ret;
}

string int2str(int n) {
    string s;
    while(n >= 1000) { s += 'M'; n -= 1000; }
    while(n >= 900) { s += "CM"; n -= 900;}
    while(n >= 500) { s += 'D'; n -= 500; }
    while(n >= 400) { s += "CD"; n -= 400;}
    while(n >= 100) { s += 'C'; n -= 100; }
    while(n >= 90) { s += "XC"; n -= 90;}
    while(n >= 50) { s += 'L'; n -= 50; }
    while(n >= 40) { s += "XL"; n -= 40;}
    while(n >= 10) { s += 'X'; n -= 10; }
    while(n >= 9) { s += "IX"; n -= 9;}
    while(n >= 5) { s += 'V'; n -= 5; }
    while(n >= 4) { s += "IV"; n -= 4;}
    while(n >= 1) { s += 'I'; n -= 1; }
    return s;
}

void solve() {
    cin>>N;
    
    int ans = 0;
    REP(i,N) {
        cin>>r;
        ans += str2int(r);
    }
    if (ans >= 4000) {
        cout << "ERROR" << endl;
    } else {
        cout << int2str(ans) << endl;
    }
}