Note:
Since in this HTML form you aren't able to enter special characters such as V̅, X̅, etc., which mean multiplying by 1000, you have to enter extra Ms for every 1000 over 3999. In other words, up to 3999 you can enter the roman numbers as they are while from 4000 you need to enter an extra M. i.e. 4025 -> MMMMXXV.