import java.io.*;
import java.util.*;
import java.math.*;

class Main289 {
	
	public static void out (Object out) {
		System.out.println(out);
	}
	
	public static void main (String[] args) throws IOException {
		BufferedReader br = 
			new BufferedReader(new InputStreamReader(System.in));
		
		int ans = 0;
		String s = br.readLine();
		
		for (int i = 0; i < s.length(); i++) {
			if ((s.charAt(i) + "").matches("[0-9]")) {
				ans += s.charAt(i) - '0';
			}
		}
		
		out(ans);
		
	}
}