package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

func configure(scanner *bufio.Scanner) {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
}
func getNextString(scanner *bufio.Scanner) string {
	scanned := scanner.Scan()
	if !scanned {
		panic("scan failed")
	}
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	extra := 0
	if os.Getenv("I") == "IronMan" {
		fp, _ = os.Open(os.Getenv("END_GAME"))
		extra = 100
	}
	scanner := bufio.NewScanner(fp)
	configure(scanner)
	writer := bufio.NewWriter(wfp)
	defer func() {
		r := recover()
		if r != nil {
			fmt.Fprintln(writer, r)
		}
		writer.Flush()
	}()
	solve(scanner, writer)
	for i := 0; i < extra; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	n := getNextInt(scanner)
	var a int
	for i := 0; i < n; i++ {
		r := getNextString(scanner)
		a += rtoa(r)
	}
	if a > 3999 {
		fmt.Fprintln(writer, "ERROR")
		return
	}
	fmt.Fprintln(writer, ator(a))
}

func rtoa(s string) int {
	m := map[string]int{
		"I":  1,
		"V":  5,
		"X":  10,
		"L":  50,
		"C":  100,
		"D":  500,
		"M":  1000,
		"IV": 4,
		"IX": 9,
		"XL": 40,
		"XC": 90,
		"CD": 400,
		"CM": 900,
	}
	var ans int
	for i := 0; i < len(s); i++ {
		if i+2 <= len(s) && m[s[i:i+2]] > 0 {
			ans += m[s[i:i+2]]
			i++
			continue
		}
		ans += m[s[i:i+1]]
	}
	return ans
}
func ator(x int) string {
	m := map[string]int{
		"I":  1,
		"V":  5,
		"X":  10,
		"L":  50,
		"C":  100,
		"D":  500,
		"M":  1000,
		"IV": 4,
		"IX": 9,
		"XL": 40,
		"XC": 90,
		"CD": 400,
		"CM": 900,
	}
	rm := map[int]string{}
	vv := make([]int, 0)
	for k, v := range m {
		rm[v] = k
		vv = append(vv, v)
	}
	sort.SliceStable(vv, func(i, j int) bool {
		return vv[i] > vv[j]
	})
	ss := make([]string, 0)
	for i := 0; i < len(vv); i++ {
		for j := 0; j < x/vv[i]; j++ {
			ss = append(ss, rm[vv[i]])
		}
		x %= vv[i]
	}
	return strings.Join(ss, "")
}