#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"

#include <random>
//#include "util.k"

using namespace std;

//呪文
#define DUMPOUT cout
#define dump(...) DUMPOUT<<"  ";DUMPOUT<<#__VA_ARGS__<<" :["<<__LINE__<<":"<<__FUNCTION__<<"]"<<endl;DUMPOUT<<"    ";dump_func(__VA_ARGS__)

typedef unsigned uint; typedef long long ll; typedef unsigned long long ull; typedef pair<int, int> pii; typedef pair<ll, ll> pll; typedef pair<double, double> pdd; typedef pair<string, string> pss;
template <typename _KTy, typename _Ty> ostream& operator << (ostream& ostr, const pair<_KTy, _Ty>& m) { ostr << "{" << m.first << ", " << m.second << "}"; return ostr; }
template <typename _KTy, typename _Ty> ostream& operator << (ostream& ostr, const map<_KTy, _Ty>& m) { if (m.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << *m.begin(); for (auto itr = ++m.begin(); itr != m.end(); itr++) { ostr << ", " << *itr; } ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const vector<_Ty>& v) { if (v.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << v.front(); for (auto itr = ++v.begin(); itr != v.end(); itr++) { ostr << ", " << *itr; }	ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const set<_Ty>& s) { if (s.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << *(s.begin()); for (auto itr = ++s.begin(); itr != s.end(); itr++) { ostr << ", " << *itr; }	ostr << "}"; return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const stack<_Ty>& s) { if (s.empty()) { ostr << "{ }"; return ostr; } stack<_Ty> t(s); ostr << "{" << t.top(); t.pop(); while (!t.empty()) { ostr << ", " << t.top(); t.pop(); } ostr << "}";	return ostr; }
template <typename _Ty> ostream& operator << (ostream& ostr, const list<_Ty>& l) { if (l.empty()) { ostr << "{ }"; return ostr; } ostr << "{" << l.front(); for (auto itr = ++l.begin(); itr != l.end(); ++itr) { ostr << ", " << *itr; } ostr << "}"; return ostr; }
template <typename _KTy, typename _Ty> istream& operator >> (istream& istr, pair<_KTy, _Ty>& m) { istr >> m.first >> m.second; return istr; }
template <typename _Ty> istream& operator >> (istream& istr, vector<_Ty>& v) { for (size_t i = 0; i < v.size(); i++) istr >> v[i]; return istr; }
namespace aux { // print tuple
	template<typename Ty, unsigned N, unsigned L> struct tp { static void print(ostream& os, const Ty& v) { os << get<N>(v) << ", "; tp<Ty, N + 1, L>::print(os, v); } };
	template<typename Ty, unsigned N> struct tp<Ty, N, N> { static void print(ostream& os, const Ty& value) { os << get<N>(value); } };
}
template<typename... Tys> ostream& operator<<(ostream& os, const tuple<Tys...>& t) { os << "{"; aux::tp<tuple<Tys...>, 0, sizeof...(Tys)-1>::print(os, t); os << "}"; return os; }

template<typename A, size_t N, typename T> inline void Fill(A(&array)[N], const T &val) { std::fill((T*)array, (T*)(array + N), val); }

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail> void dump_func(Head&& head, Tail&&... tail) { DUMPOUT << head; if (sizeof...(Tail) == 0) { DUMPOUT << " "; } else { DUMPOUT << ", "; } dump_func(std::move(tail)...); }

#define PI 3.14159265358979323846
#define EPS 1e-11
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define all(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define fake false



string to_roman(int n) {
	string res;
	int M = n / 1000;
	res += string(M, 'M');
	n %= 1000;
	int CM = n / 900;
	res += (CM ? "CM" : "");
	n %= 900;
	int D = n / 500;
	res += string(D, 'D');
	n %= 500;
	int CD = n / 400;
	res += (CD ? "CD" : "");
	n %= 400;
	int C = n / 100;
	res += string(C, 'C');
	n %= 100;
	int XC = n / 90;
	res += (XC ? "XC" : "");
	n %= 90;
	int L = n / 50;
	res += string(L, 'L');
	n %= 50;
	int XL = n / 40;
	res += (XL ? "XL" : "");
	n %= 40;
	int X = n / 10;
	res += string(X, 'X');
	n %= 10;
	int IX = n / 9;
	res += (IX ? "IX" : "");
	n %= 9;
	int V = n / 5;
	res += string(V, 'V');
	n %= 5;
	int IV = n / 4;
	res += (IV ? "IV" : "");
	n %= 4;
	int I = n;
	res += string(I, 'I');
	return res;
}

int main()
{
	//clock_t start, end;
	//start = clock();

	//cin.tie(0);
	//ios::sync_with_stdio(false);

	map<string, int> rtoi;
	map<int, string> itor;

	for (int i = 1; i < 4000; i++) {
		string r = to_roman(i);
		rtoi[r] = i;
		itor[i] = r;
	}

	int N;
	cin >> N;

	vector<string> R(N);
	cin >> R;

	int sum = 0;
	for (int i = 0; i < N; i++) {
		sum += rtoi[R[i]];
	}
	cout << (sum < 4000 ? itor[sum] : "ERROR") << endl;

	//end = clock();
	//printf("%d msec.\k", end - start);

	return 0;
}