_ = gets.to_i
nums = gets.chomp.split

sum = 0
nums.each do |num|
  result = 0
  pos = 0
  while pos <= num.size
    case num[pos]
    when "I"
      if num[pos + 1] == "V"
        result += 4
        pos += 1
      elsif num[pos + 1] == "X"
        result += 9
        pos += 1
      else
        result += 1
      end
    when "V"
      result += 5
    when "X"
      if num[pos + 1] == "L"
        result += 40
        pos += 1
      elsif num[pos + 1] == "C"
        result += 90
        pos += 1
      else
        result += 10
      end
    when "L"
      result += 50
    when "D"
      result += 500
    when "C"
      if num[pos + 1] == "D"
        result += 400
        pos += 1
      elsif num[pos + 1] == "M"
        result += 900
        pos += 1
      else
        result += 100
      end
    when "M"
      result += 1000
    end
    pos += 1
  end

  sum += result
end

res = ""
res += "M" * (sum / 1000).floor
rest = sum % 1000
if (rest / 100).floor == 4
  res += "CD"
elsif (rest / 100).floor == 9
  res += "CM"
elsif (rest / 100).floor >= 5
  res += "D" + "C" * ((rest / 100).floor - 5)
else
  res += "C" * (rest / 100).floor
end

rest = rest % 100
if (rest / 10).floor == 4
  res += "XL"
elsif (rest / 10).floor == 9
  res += "XC"
elsif (rest / 10).floor >= 5
  res += "L" + "X" * ((rest / 10).floor - 5)
else
  res += "X" * (rest / 10).floor
end

rest = rest % 10
if rest == 4
  res += "IV"
elsif rest == 9
  res += "IX"
elsif rest >= 5
  res += "V" + "I" * (rest - 5)
else
  res += "I" * rest
end

puts sum > 3999 ? "ERROR" : res