import java.util.Scanner;

public class Yukicoder39 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		char[] c = sc.next().toCharArray();
		
		char buf;
		int max = -1;
		for (int i = 0; i < c.length - 1; i++) {
			for (int j = i + 1; j < c.length; j++) {
				buf = c[i];
				c[i] = c[j];
				c[j] = buf;

				max = Math.max(max, Integer.parseInt(String.valueOf(c)));
				
				buf = c[i];
				c[i] = c[j];
				c[j] = buf;

			}
		}
		System.out.println(max);
	}
}