def r2a(r):
    c2v = {'I':1, 'V':5, 'X':10, 'L':50, 'C':100, 'D':500, 'M':1000}
    r = r.replace('IV', 'IIII')
    r = r.replace('IX', 'VIIII')
    r = r.replace('XL', 'XXXX')
    r = r.replace('XC', 'LXXXX')
    r = r.replace('CD', 'CCCC')
    r = r.replace('CM', 'DCCCC')
    return sum(c2v[c] for c in r)

def a2r(a):
    if a > 3999:
        return "ERROR"
    r = []
    while (a >= 1000):
        r.append('M')
        a -= 1000
    while (a >= 500):
        r.append('D')
        a -= 500
    while (a >= 100):
        r.append('C')
        a -= 100
    while (a >= 50):
        r.append('L')
        a -= 50
    while (a >= 10):
        r.append('X')
        a -= 10
    while (a >= 5):
        r.append('V')
        a -= 5
    while (a >= 1):
        r.append('I')
        a -= 1
    r = ''.join(r)
    r = r.replace('DCCCC', 'CM')
    r = r.replace('CCCC', 'CD')
    r = r.replace('LXXXX', 'XC')
    r = r.replace('XXXX', 'XL')
    r = r.replace('VIIII', 'IX')
    r = r.replace('IIII', 'IV')
    return r

def solve(N, Rs):
    a = sum(map(r2a, Rs))
    return a2r(a)

def read_data():
    N = int(input())
    Rs = list(input().split())
    return N, Rs

N, Rs = read_data()
print(solve(N, Rs))