#include <iostream>
#include <string>

using namespace std;

int from_rome(string r){
    int ret = 0;
    for(int i=0;i<r.length();i++){
        if(r[i] == 'I'){
            if(r[i+1] == 'V') ret += 4, i++;
            else if(r[i+1] == 'X') ret += 9, i++;
            else              ret += 1;
        }else if(r[i] == 'V'){
            ret += 5;
        }else if(r[i] == 'X'){
            if(r[i+1] == 'L') ret += 40, i++;
            else if(r[i+1] == 'C') ret += 90, i++;
            else        ret += 10;
        }else if(r[i] == 'L'){
            ret += 50;
        }else if(r[i] == 'C'){
            if(r[i+1] == 'D') ret += 400, i++;
            else if(r[i+1] == 'M') ret += 900, i++;
            else            ret += 100;
        }else if(r[i] == 'D'){
            ret += 500;
        }else if(r[i] == 'M'){
            ret += 1000;
        }
    }
    return ret;
}

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

string to_rome(int n){
    string ret;
    for(int i=0;i<14;i++){
        if(n == 0) break;
        while(n >= nums[i]){
            ret += dig[i];
            n -= nums[i];
        }
    }
    return ret;
}

int main(){
    string r;
    int N;
    cin >> N;
    int sum = 0;
    for(int i=0;i<N;i++){
        cin >> r;
        sum += from_rome(r);
    }
    if(sum > 3999) cout << "ERROR" << endl;
    else cout << to_rome(sum) << endl;
    return 0;
}