import java.util.*;
public class A{
	static Scanner s = new Scanner(System.in);
	public static void main(String[] args) {
		char in[] = s.next().toCharArray();
		int result=0;
		for(int i=0;i<in.length;i++) {
			if('0'<=in[i]&&in[i]<='9') {
				result+=in[i]-'0';
			}
		}
		System.out.println(result);
	}
}