Please need help... I need to check if the given value is VALID or INVALID in roman number...

Write a program to accept a roman numeral and determine if it is valid. You do not need to convert the numeral, just determine if it is valid. This is based on the problem from https://projecteuler.net/problem=89. You can go there for more information. and a set of roman numeral samples. and then;

Modify the last assignment so that the user enters a file name containing roman numerals. For each roman numeral in the file print out that numeral and a determination of validity (VALID/NOT VALID).