Try to learn more about Roman number.
Complete the addition of Roman number directly, not convert to Arabic number(0-9).
Reference to class "kingcaesar.math.RomanNumber"
Step 1. Uncompact Roman number.
Step 2. Concatenate two uncompacted Roman number togeter.
Step 3. Grouping and sorting result from step2 by bigger symbol on the left.
Step 4. Combine same symbols to bigger symbols.
Step 5. Compact the result before return.

You can import this project to eclipse or your IDE and try to run main method at class "App".
The execution need input.txt file that provided in project already.
You can edit or add addition of Roman number for testing my code.
If there any comment or suggestion please let me know.

You can also run this program without Import project.
Step 1. Download file https://github.com/jackiekolv/roman-number/raw/master/roman-number-1.0.0.jar
Step 2. Download file https://github.com/jackiekolv/roman-number/raw/master/input.txt
Step 3. Put both of them in the same directory.
Step 4. In that directory run command "java -jar roman-number-1.0.0.jar".
Step 5. Try to check the result (May use this site to double check: http://www.onlineconversion.com/roman_numerals_advanced.htm).