import sys

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

ara_nums = []
for i in rom_nums:
    for j in range(len(i) - 1):
        if rom_dic[i[j]] >= rom_dic[i[j + 1]]:
            ara_nums.append(rom_dic[i[j]])
        else:
            ara_nums.append(-(rom_dic[i[j]]))
    ara_nums.append(rom_dic[i[-1]])
ara_sum = sum(ara_nums)
ara_sum_str = str(ara_sum)

if 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]

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

print("".join(rom_sum))