#include<bits/stdc++.h>
#define ALL(v) std::begin(v),std::end(v)
using lint=long long;
using lubl=long double;
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    std::string digits="IVXLCDM";
    std::vector<std::string>roman{
        "",
        "I",
        "II",
        "III",
        "IV",
        "V",
        "VI",
        "VII",
        "VIII",
        "IX",
    };
    auto toroman=[&](lint x){
        std::string ans;
        for(lint i=3;i>=0;i--){
            lint j=x;
            for(lint k=0;k<i;k++)j/=10;
            j%=10;
            std::string s=roman.at(j);
            for(char c:s){
                ans.push_back(*(2*i+std::find(ALL(digits),c)));
            }
        }
        return ans;
    };
    std::vector<std::string>table(4000);
    for(lint i=1;i<4000;i++){
        table.at(i)=toroman(i);
    }
    lint n;std::cin>>n;
    lint ans=0;
    while(n--){
        std::string s;std::cin>>s;
        ans+=std::find(ALL(table),s)-table.begin();
    }
    if(4000<=ans){
        std::cout<<"ERROR"<<'\n';
        return 0;
    }
    std::cout<<table.at(ans)<<'\n';
}