#include <bits/stdc++.h>
#define rep(i, a) for (int i = (int)0; i < (int)a; ++i)
#define rrep(i, a) for (int i = (int)a - 1; i >= 0; --i)
#define REP(i, a, b) for (int i = (int)a; i < (int)b; ++i)
#define RREP(i, a, b) for (int i = (int)a - 1; i >= b; --i)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define popcount __builtin_popcount
using ll = long long;
constexpr ll mod = 1e9 + 7;
constexpr ll INF = 1LL << 60;

template <class T>
inline bool chmin(T &a, T b)
{
	if (a > b)
	{
		a = b;
		return true;
	}
	return false;
}
template <class T>
inline bool chmax(T &a, T b)
{
	if (a < b)
	{
		a = b;
		return true;
	}
	return false;
}

ll gcd(ll n, ll m)
{
	ll tmp;
	while (m != 0)
	{
		tmp = n % m;
		n = m;
		m = tmp;
	}
	return n;
}

ll lcm(ll n, ll m)
{
	return abs(n) / gcd(n, m) * abs(m); //gl=xy
}

using namespace std;

void solve()
{
	int n;
	cin>>n;
	vector<string>r(n);
	rep(i,n)cin>>r[i];
	map<string,int>mp;
	mp["I"]=1;mp["V"]=5;mp["X"]=10;mp["L"]=50;mp["C"]=100;mp["D"]=500;mp["M"]=1000;
	mp["IV"]=4;mp["IX"]=9;mp["XL"]=40;mp["XC"]=90;mp["CD"]=400;mp["CM"]=900;
	int ans=0;
	rep(i,n){
		rep(j,r[i].size()){
			if(j<r[i].size()-1&&mp[string{r[i][j]}]<mp[string{r[i][j+1]}]){
				string t=string{r[i][j]}+string{r[i][j+1]};
				ans+=mp[t];
				++j;
			}
			else{
				ans+=mp[string{r[i][j]}];
			}
		}
	}
	if(ans>3999){
		cout<<"ERROR\n";
	}
	else{
		map<int,string>mp2;
		for(auto z:mp){
			mp2[z.second]=z.first;
		}
		string s="";
		int mul=1;
		if(ans>=1000)mul=1000;
		else if(ans>=100)mul=100;
		else if(ans>=10)mul=10;
		while(ans>0){
			int x=ans/mul;
			//cout<<ans<<endl;
			if(x==9){
				s+=mp2[x*mul];
				ans-=x*mul;
				mul/=10;
			}
			else if(x>=5){
				s+=mp2[5*mul];
				ans-=5*mul;
				if(x==5) mul/=10;
			}
			else if(x==4){
				s+=mp2[x*mul];
				ans-=x*mul;
				mul/=10;
			}
			else if(x>0){
				rep(i,x){
					s+=mp2[mul];
				}
				ans-=x*mul;
				mul/=10;
			}
			else mul/=10;
		}
		cout<<s<<"\n";
	}
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(15);
	solve();
	return 0;
}