C = {'I': 1, 'II': 2, 'III': 3, 'IV': 4, 'V': 5,
     'VI': 6, 'VII': 7, 'VIII': 8, 'IX': 9, 'X': 10,
     'XX': 20, 'XXX': 30, 'XL': 40, 'L': 50,
     'LX': 60, 'LXX': 70, 'LXXX': 80, 'XC': 90, 'C': 100,
     'CC': 200, 'CCC': 300, 'CD': 400, 'D': 500,
     'DC': 600, 'DCC': 700, 'DCCC': 800, 'CM': 900, 'M': 1000,
     'MM': 2000, 'MMM': 3000}
D = {1: 'I', 2: 'II', 3: 'III', 4: 'IV', 5: 'V',
     6: 'VI', 7: 'VII', 8: 'VIII', 9: 'IX', 10: 'X', 
     20: 'XX', 30: 'XXX', 40: 'XL', 50: 'L',
     60: 'LX', 70: 'LXX', 80: 'LXXX', 90: 'XC', 100: 'C',
     200: 'CC', 300: 'CCC', 400: 'CD', 500: 'D',
     600: 'DC', 700: 'DCC', 800: 'DCCC', 900: 'CM', 1000: 'M',
     2000: 'MM', 3000: 'MMM'}

n = int(input())
R = list(input().split())

ans = 0
for i in range(n):
    r = R[i]
    l = len(r)
    idx = 0
    while idx < l:
        for d in range(4, 0, -1):
            if idx + d <= l and r[idx:idx + d] in C:
                ans += C[r[idx:idx + d]]
                idx += d
                break
if ans > 3999:
    print("ERROR")
else:
    res = ''
    th, ans = divmod(ans, 1000)
    h, ans = divmod(ans, 100)
    te, o = divmod(ans, 10)
    if th > 0:
        res += D[th * 1000]
    if h > 0:
        res += D[h * 100]
    if te > 0:
        res += D[te * 10]
    if o > 0:
        res += D[o]
    print(res)