import java.util.Scanner;
 
class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		int ans = 0;
		char[] c = s.toCharArray();
		for(char cc : c){
			if(Character.isDigit(cc)){
				ans += Character.digit(cc, 10);
			}
		}
		System.out.println(ans);
	}
}