#include "bits/stdc++.h"
#define REP(i,n,N) for(ll i=(n); i<(N); i++)
#define RREP(i,n,N) for(ll i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const ll mod = 1e9+7;

int main() {
    vector<int> a(256);
    string u = "IVXLCDM";
    int v[] = { 1, 5, 10, 50, 100, 500, 1000 };

    auto f = [&](char c) {
        return v[u.find(c)];
    };

    int n;
    cin >> n;

    int sum = 0;
    while (n--) {
        string s;
        cin >> s;
        int val = 0;
        for (int i = s.size() - 1; i >= 0; i--) {
            if (i + 1 < s.size() && f(s[i]) < f(s[i + 1])) {
                val -= f(s[i]);
            } else {
                val += f(s[i]);
            }
        }
        sum += val;
    }

    if (sum >= 4000) {
        cout << "ERROR" << endl;
        return 0;
    }

    string ans;
    for (int i = 6; i >= 0; i -= 2) {
        int cnt = 0;
        while (sum - v[i] >= 0) {
            sum -= v[i];
            cnt++;
        }
        if (cnt == 4) {
            ans += u[i];
            ans += u[i + 1];
        } else if (cnt == 9) {
            ans += u[i];
            ans += u[i + 2];
        } else if (cnt >= 5) {
            ans += u[i + 1];
            ans += string(cnt - 5, u[i]);
        } else {
            ans += string(cnt, u[i]);
        }
    }
    cout << ans << endl;
}