import sys

n = int(input())
rom_nums = input().split()
rom_dic = {"I":1, "V": 5, "X":10, "L":50, "C":100, "D":500, "M":1000}
ara_num = 0
rom_sum = ""

for i in rom_nums:
    for j in range(len(i) - 1):
        if rom_dic[i[j]] >= rom_dic[i[j + 1]]:
            ara_num += rom_dic[i[j]]
        else:
            ara_num -= rom_dic[i[j]]
    ara_num += rom_dic[i[-1]]
ara_sum = str(ara_num)

if int(ara_sum) > 3999:
    print("ERROR")
    sys.exit(0)

def get_key(a_num):
    return [k for k, v in rom_dic.items() if v == a_num][0]

for i in range(len(ara_sum)):
    digit = 10 ** (len(ara_sum) - 1 - i)
    if int(ara_sum[i]) == 4:
        rom_sum += (get_key(digit) + get_key(5 * digit))
    elif int(ara_sum[i]) == 9:
        rom_sum += (get_key(digit) + get_key(10 * digit))
    elif 0 <= int(ara_sum[i]) <= 3:
        rom_sum += (get_key(digit) * int(ara_sum[i]))
    else:
        rom_sum += (get_key(5 * digit) + get_key(digit) * (int(ara_sum[i]) - 5))

print(rom_sum)