<?php
$n = trim(fgets(STDIN));
$n_array = array();
// 1桁ずつ分解する
for ( $i=0; $i<strlen($n); $i++ ) {
	$n_array[] = intval(substr($n,$i,1));
}
for ( $max=9; $max>0; $max-- ) {
	for ( $i=count($n_array)-1; $i>=0; $i-- ) {
		if ( $n_array[$i] == $max ) {
			for ( $j=0; $j<$i; $j++ ) {
				if ( $n_array[$j] < $n_array[$i] ) {
					swap($n_array[$j], $n_array[$i]);
					break 3;
				}
			}
		}
	}
}
echo implode("", $n_array).PHP_EOL;

function swap (&$a, &$b) {
	$t = $a;
	$a = $b;
	$b = $t;
}