/** * Problem 1 [30pts]. According To Historians, Julius Caesar Used The Following Encryption * Technique For Sending Messages. Given A String S And An Integer K, Replace Every Letter By * The Letter Than Comes K Positions Later In Alphabetical Order. For Example The String Hello * With Key 5, Is Encrypted Into Mjqqt Since Letter M Is

/**
	* Problem 1 [30pts]. According to historians, Julius Caesar used the following encryption
	* technique for sending messages. Given a string s and an integer k, replace every letter by
	* the letter than comes k positions later in alphabetical order. For example the string hello
	* with key 5, is encrypted into mjqqt since letter m is the fifth letter after h and so on.
	* Note that z in this case is mapped to e (since after z we go back to a). To decrypt the
	* message one needs to know the key; for our example, just shift each letter by -5 positions.
	* In this problem you will write a program called Cipher.java which does both encryption
	* and decryption. Some examples follow
	* -- Enter the text below
	* Hello
	* -- Enter E for Encryption, D for Decryption, X to exit: E
	* -- Enter key: 5
	* -- The encrypted text is below
	* Mjqqt
	* Now another example
	* -- Enter the text below
	* Mjqqt
	* -- Enter E for Encryption, D for Decryption, X to exit: D
	* -- Enter key: 5
	* -- The decrypted text is below
	* Hello
	* Another example
	* -- Enter the text below
	* Hello
	* -- Enter E for Encryption, D for Decryption, X to exit: F
	* -- Input not recognized. Try again.
	* -- Enter E for Encryption, D for Decryption, X to exit: X
	* NOTE: You can assume that the input contain only alphabet letters, both lower case and
	* upper case, space, and the usual punctuation marks {., !?}. Non alphabet characters are to
	* be left unchanged. Also, you must keep the case; i.e. a lower case letter should be mapped
	* to a lower case letter.
	* NOTE: The key k is a positive integer. But, it can be a large number. In this case, you
	* must wrap it around. For example if the key is 27 then a is mapped to b etc. Your code is
	* expected to work with any non-negative integer. Please check that input key is valid (that
	* is key 0; if not print an error message and exit).
	*/
	public class Problem1 {
	// start your code here
	}