#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if (y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if (x < y) x = y; }

void toRomanNumber1(char i, char v, char x, int n, string &s) {
	switch (n) {
	case 0: break;
	case 1: s += i; break;
	case 2: s += i, s += i; break;
	case 3: s += i, s += i, s += i; break;
	case 4: s += i, s += v; break;
	case 5: s += v; break;
	case 6: s += v, s += i; break;
	case 7: s += v, s += i, s += i; break;
	case 8: s += v, s += i, s += i, s += i; break;
	case 9: s += i, s += x; break;
	default: break;
	}
}

string toRomanNumber(int n) {
	string s(n / 1000, 'M');
	toRomanNumber1('C', 'D', 'M', n / 100 % 10, s);
	toRomanNumber1('X', 'L', 'C', n / 10 % 10, s);
	toRomanNumber1('I', 'V', 'X', n % 10, s);
	return s;
}
int main() {
	map<string, int> a;
	rer(i, 1, 3999) {
		a[toRomanNumber(i)]=i;
	}
	int N;
	while (~scanf("%d", &N)) {
		int sum = 0;
		rep(i, N) {
			char buf[101];
			scanf("%s", buf);
			sum+=a[buf];
		}
		if (sum > 3999) {
			puts("ERROR");
		} else {
			string ans = toRomanNumber(sum);
			puts(ans.c_str());
		}
	}
	return 0;
}