import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		char[] s = sc.next().toCharArray();
		sc.close();

		int max = 0;
		int min = 9;
		for (int i = 0; i < s.length; i++) {
			max = Math.max(max, s[i] - '0');
			min = Math.min(min, s[i] - '0');
		}
		System.out.println(max - min);
	}
}