#include <bits/stdc++.h>
using namespace std;

typedef long long   signed int LL;
typedef long long unsigned int LU;

#define incID(i, l, r) for(int i = (l)    ; i <  (r); i++)
#define incII(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define decII(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define  inc(i, n) incID(i, 0, n)
#define inc1(i, n) incII(i, 1, n)
#define  dec(i, n) decID(i, 0, n)
#define dec1(i, n) decII(i, 1, n)

#define inII(v, l, r) ((l) <= (v) && (v) <= (r))
#define inID(v, l, r) ((l) <= (v) && (v) <  (r))

#define PB push_back
#define EB emplace_back
#define MP make_pair
#define FI first
#define SE second
#define UB upper_bound
#define LB lower_bound
#define PQ priority_queue

#define  ALL(v)  v.begin(),  v.end()
#define RALL(v) v.rbegin(), v.rend()
#define  FOR(it, v) for(auto it =  v.begin(); it !=  v.end(); ++it)
#define RFOR(it, v) for(auto it = v.rbegin(); it != v.rend(); ++it)

template<typename T> bool   setmin(T & a, T b) { if(b <  a) { a = b; return true; } else { return false; } }
template<typename T> bool   setmax(T & a, T b) { if(b >  a) { a = b; return true; } else { return false; } }
template<typename T> bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } }
template<typename T> bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } }
template<typename T> T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); }
template<typename T> T lcm(T a, T b) { return a / gcd(a, b) * b; }

// ---- ----

string rm[13] = { "IV", "IX", "XL", "XC", "CD", "CM", "I", "V", "X", "L", "C", "D", "M" };
int   val[13] = {    4,    9,   40,   90,  400,  900,   1,   5,  10,  50, 100, 500, 1000 };

int r2i(string s) {
	int v = 0;
	s += "@";
	inc(i, s.size()) {
		inc(j, 13) {
			if(s.substr(i, rm[j].size()) == rm[j]) {
				v += val[j];
				i += (rm[j].size() - 1);
				break;
			}
		}
	}
	return v;
}

string t4[ 4] = { "", "M", "MM", "MMM", };
string t3[10] = { "", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM" };
string t2[10] = { "", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC" };
string t1[10] = { "", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX" };

int n;
string r[100];

int main() {
	cin >> n;
	inc(i, n) { cin >> r[i]; }
	
	int sum = 0;
	inc(i, n) { sum += r2i(r[i]); }
	
	if(sum >= 4000) {
		cout << "ERROR" << endl;
	} else {
		string ans;
		ans += (t4[sum / 1000]); sum %= 1000;
		ans += (t3[sum /  100]); sum %=  100;
		ans += (t2[sum /   10]); sum %=   10;
		ans += (t1[sum /    1]);
		cout << ans << endl;
	}
	
	return 0;
}