package main

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

var sc = bufio.NewScanner(os.Stdin)
var wr = bufio.NewWriter(os.Stdout)

func out(x ...interface{}) {
	fmt.Fprintln(wr, x...)
}

func getI() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

func getF() float64 {
	sc.Scan()
	i, e := strconv.ParseFloat(sc.Text(), 64)
	if e != nil {
		panic(e)
	}
	return i
}

func getInts(N int) []int {
	ret := make([]int, N)
	for i := 0; i < N; i++ {
		ret[i] = getI()
	}
	return ret
}

func getS() string {
	sc.Scan()
	return sc.Text()
}

// min, max, asub, absなど基本関数
func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

// min for n entry
func nmin(a ...int) int {
	ret := a[0]
	for _, e := range a {
		ret = min(ret, e)
	}
	return ret
}

// max for n entry
func nmax(a ...int) int {
	ret := a[0]
	for _, e := range a {
		ret = max(ret, e)
	}
	return ret
}

func asub(a, b int) int {
	if a > b {
		return a - b
	}
	return b - a
}

func abs(a int) int {
	if a >= 0 {
		return a
	}
	return -a
}

func lowerBound(a []int, x int) int {
	idx := sort.Search(len(a), func(i int) bool {
		return a[i] >= x
	})
	return idx
}

func upperBound(a []int, x int) int {
	idx := sort.Search(len(a), func(i int) bool {
		return a[i] > x
	})
	return idx
}

var num = map[string]int{
	"I": 1,
	"V": 5,
	"X": 10,
	"L": 50,
	"C": 100,
	"D": 500,
	"M": 1000,
}

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

var maxTable = []int{
	1000,
	900,
	500,
	400,
	100,
	90,
	50,
	40,
	10,
	9,
	5,
	4,
	1,
}

// Roman is roman
type Roman struct{}

// NewRoman to create a Roman
func NewRoman() *Roman {
	return &Roman{}
}

// ToNumber to covert roman numeral to decimal
func (r *Roman) ToNumber(n string) int {
	out := 0
	ln := len(n)
	for i := 0; i < ln; i++ {
		c := string(n[i])
		vc := num[c]
		if i < ln-1 {
			cnext := string(n[i+1])
			vcnext := num[cnext]
			if vc < vcnext {
				out += vcnext - vc
				i++
			} else {
				out += vc
			}
		} else {
			out += vc
		}
	}
	return out
}

// ToRoman is to convert decimal number to roman numeral
func (r *Roman) ToRoman(n int) string {
	out := ""
	for n > 0 {
		v := highestDecimal(n)
		out += numInv[v]
		n -= v
	}
	return out
}

func highestDecimal(n int) int {
	for _, v := range maxTable {
		if v <= n {
			return v
		}
	}
	return 1
}

func main() {
	defer wr.Flush()
	sc.Split(bufio.ScanWords)
	sc.Buffer([]byte{}, 1000000)
	// this template is new version.
	// use getI(), getS(), getInts(), getF()
	N := getI()
	r := NewRoman()
	tot := 0
	for i := 0; i < N; i++ {
		s := getS()
		tot += r.ToNumber(s)
	}

	if tot > 3999 {
		out("ERROR")
		return
	}
	out(r.ToRoman(tot))
}