import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
	String str = sc.next();
	char[] s = str.toCharArray();
	int ret = 0;

	for(char c:s) {
            if (c>='0' && c<='9') {
	        ret += c - '0';
	    }
        }

        System.out.println(ret);
    }
}