Roman to Integer 

/**
	 * 
	 * Given a roman numeral, convert it to an integer.
	 * 
	 * Input is guaranteed to be within the range from 1 to 3999.
	 * 
	 * 4 IV 3 IIV 6 VI
	 * 
	 * 123 CXXIII 1139 MCXXXIX
	 */