package yukicoder;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) {
		BufferedReader buff = new BufferedReader(new InputStreamReader(System.in));

		try {
			String line = buff.readLine();
			int[] count = new int[10];
			for(int i = 0; i < line.length(); ++i){
				++count[Integer.parseInt(String.valueOf(line.charAt(i)))];
			}

			for(int i = 9; i >= 0; --i){
				for(int j = 0; j < count[i]; ++j){
					System.out.print(i);
				}
			}

			System.out.println();
		} catch (Exception e) {
			e.getStackTrace();
		}
	}
}