import java.util.*;
import java.lang.*;
import java.io.*;
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner s = new Scanner(System.in);
		while (s.hasNext()) {
			String[] d = s.nextLine().split(" ");
			Arrays.sort(d, new C());
			for (String i : d) System.out.print(i);
			System.out.println();
		}
		s.close();
	}
	private static class C implements Comparator<String> {
		@Override
		public int compare(String a, String b) {
			for (int i = 0, c = a.length(), d = b.length(), l = c < d ? d : c, e;i < l;++ i) if ((e = a.charAt(i % c) - b.charAt(i % d)) != 0) return e;
			return 0;
		}
	}
}

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MyAyIDEKMSAyIDIxCjEgMiAzIDQgNSA2IDcgOCA5IDEwIDExIDEyIDEzIDE0IDE1IDE2

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