import java.io.*;
import java.math.*;
import java.util.*;
import java.awt.geom.*;

import static java.lang.Math.*;

public class Solution implements Runnable {

    public static void main(String[] args) throws Exception {
        new Thread(null, new Solution(), "", 1 << 25).start();
    }

    BufferedReader in;
    PrintWriter out;
    StringTokenizer st;

    final String fname = "";

    private String next() throws Exception {
        if (st == null || !st.hasMoreElements())
            st = new StringTokenizer(in.readLine());
        return st.nextToken();
    }

    private int nextInt() throws Exception {
        return Integer.parseInt(next());
    }

    private long nextLong() throws Exception {
        return Long.parseLong(next());
    }

    private double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }

    public void run() {
        try {
            //in = new BufferedReader(new FileReader(fname+".in"));
            //out = new PrintWriter(new FileWriter(fname+".out"));
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(new OutputStreamWriter(System.out));
            solve();
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        } finally {
            out.close();
        }
    }

    String s[]=new String [4000];

    int memo[]=new int[127];

    String ans="";

    void check(int nums[]) {
        int cnt[]=new int[127];
        int md=1;
        String t = "";
        for (int i=0;i<nums.length;i++) {
            nums[i]=nums[i]*md;
            md*=10;
        }
        for (int i=nums.length-1;i>=0;i--) {
            if (nums[i]==0) continue;
            t+=s[nums[i]];
            for (int j=0;j<s[nums[i]].length();j++) {
                cnt[s[nums[i]].charAt(j)]++;
                if (cnt[s[nums[i]].charAt(j)]>memo[s[nums[i]].charAt(j)]) return;
            }
        }
        if (t.length()>ans.length())
            ans=t;
    }

    public void solve() throws Exception {
        s[1]="I";
        s[2]="II";
        s[3]="III";
        s[4]="IV";
        s[5]="V";
        s[6]="VI";
        s[7]="VII";
        s[8]="VIII";
        s[9]="IX";
        s[10]="X";
        s[20]="XX";
        s[30]="XXX";
        s[40]="XL";
        s[50]="L";
        s[60]="LX";
        s[70]="LXX";
        s[80]="LXXX";
        s[90]="XC";
        s[100]="C";
        s[200]="CC";
        s[300]="CCC";
        s[400]="CD";
        s[500]="D";
        s[600]="DC";
        s[700]="DCC";
        s[800]="DCCC";
        s[900]="CM";
        s[1000]="M";
        s[2000]="MM";
        s[3000]="MMM";
        String t = in.readLine();
        for (int i=0;i<t.length();i++) {
            if (t.charAt(i)>='a' && t.charAt(i)<='z') {
                memo[Character.toUpperCase(t.charAt(i))]++;
            }
            if (t.charAt(i)>='A' && t.charAt(i)<='Z')
                memo[t.charAt(i)]++;
        }
        for (int num=3999;num>=1;num--) {
            int tmp=num;
            int nums[]=new int [4];
            int it=0;
            while (tmp>0) {
                nums[it++]=tmp%10;
                tmp/=10;
            }
            check(nums);
        }
        out.println(ans);
    }
}