Problem:
Toggling Cases

Write a program which converts uppercase/lowercase letters to lowercase/uppercase for a given string.

Input

A string is given in a line.

Output

Print the converted string in a line. Note that you do not need to convert any characters other than alphabetical letters.

Constraints

The length of the input string < 1200

Sample Input

fAIR, LATER, OCCASIONALLY CLOUDY.

Sample Output

Fair, later, occasionally cloudy.

Solution in JAVA (judge verdict: Accepted)

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO ?????????????????????????????????????????????
		
		Scanner scan = new Scanner(System.in);
		scan.useDelimiter("?\?\r?\?\n");
		// ??\???
		String s = scan.next();
		// ??????????????????
		int s1 = s.length();
		
		String S = "";
		for(int i=0; i<s1; i++){
			String s2 = s.substring(i, i+1);
			String s3;
			if( s2.matches( "[a-z]+" ) ){
				String upper_s2 = s2.toUpperCase();
				S = S + upper_s2;
			}
			/*
			else if (s2 == a){
				
				S = S + s3;
			}
			*/
			else {
				String lower_s2 = s2.toLowerCase();
				S = S + lower_s2;
			}
		}
		
		System.out.print(S);

	}

}