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 PHP (judge verdict: Accepted)

<?php

$str = trim(fgets(STDIN));
for ($i = 0, $len = strlen($str); $i < $len; $i++) {
    $c = $str[$i];
    if (preg_match('/[a-z]/', $c)) {
        echo strtoupper($c);
    } elseif (preg_match('/[A-Z]/', $c)) {
        echo strtolower($c);
    } else {
        echo $c;
    }
}

echo PHP_EOL;