import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		int sum = 0;
		for (int i = 0; i < s.length(); i++) {
			if (s.charAt(i) >= '0' && s.charAt(i) <= '9') {
				sum += s.charAt(i) - '0';
			}
		}
		System.out.println(sum);
	}
}