# Validating Roman Numerals in Python – HackerRank Solution

You are given a string, and you have to validate whether it’s a valid Roman numeral. If it is valid, print True. Otherwise, print False. Try to create a regular expression for a valid Roman numeral.

#### Input Format :

A single line of input containing a string of Roman characters.

#### Output Format :

Output a single line containing True or False according to the instructions above.

#### Constraints :

The number will be between 1 and 3999(both included).

```CDXXI
```

```True
```

#### References :

Regular expressions are a key concept in any programming language. A quick explanation with Python examples is available here. You could also go through the link below to read more about regular expressions in Python.

### Validating Roman Numerals in Python – HackerRank Solution

```thousand = 'M{0,3}'
hundred = '(C[MD]|D?C{0,3})'
ten = '(X[CL]|L?X{0,3})'
digit = '(I[VX]|V?I{0,3})'
regex_pattern = r"%s%s%s%s\$" % (thousand, hundred, ten, digit)
# Do not delete 'r'.
# Validating Roman Numerals in Python - Hacker Rank Solution END
import re
print(str(bool(re.match(regex_pattern, input()))))```

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