#include<bits/stdc++.h>
#define LL long long
#define LLL __int128
#define uint unsigned
#define ldb long double
#define uLL unsigned long long
using namespace std;
vector<vector<string>>A({
    vector<string>({"","M","MM","MMM"}),
    vector<string>({"","C","CC","CCC","CD","D","DC","DCC","DCCC","CM"}),
    vector<string>({"","X","XX","XXX","XL","L","LX","LXX","LXXX","XC"}),
    vector<string>({"","I","II","III","IV","V","VI","VII","VIII","IX"})
});
const int N=1e5+5;
int n;
int f[N],pre[N];
string s;
vector<string>B;
inline void write(int x){
    if(x-pre[x])write(x-pre[x]);
    cout<<s.substr(x-pre[x]+1,pre[x])<<'\n';
}
signed main(){
    cin.tie(0)->sync_with_stdio(0);
    for(auto i:A[0])
        for(auto j:A[1])
            for(auto k:A[2])
                for(auto l:A[3]){
                    auto s=i+j+k+l,t=s;
                    reverse(t.begin(),t.end());
                    if(!s.empty()&&s==t)B.emplace_back(s);
                }
    cin>>n>>s,s=" "+s;
    for(int i=1;i<=n;++i){
        f[i]=n+1;
        for(auto t:B)
            if(i>=t.length()&&s.substr(i-t.length()+1,t.length())==t){
                int w=f[i-t.length()]+1;
                if(w<f[i])f[i]=w,pre[i]=t.length();
            }
    }
    cout<<f[n]<<'\n';
    write(n);
    return 0;
}
/*
*/