Create a class HugeInteger that uses a $40-$element array of digits to store integers as large as $40$ digits each. Provide member functions input, output, add and subtract. For comparing HugeInteger objects, provide functions isEqualTo, isNotEqualTo, isGreaterThan, isLessThan, simply returns true if the relationship holds between the two HugeIntegers and returns false if the relationship does not hold. Note: separate interface from implementation!

Write in C$++$