import java.util.*;

class No0289{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		String str = sc.next();
		char[] s = str.toCharArray();
		int result = 0;
		
		for(int i  = 0; i < s.length; i++){
			if(s[i] >= '0' && s[i] <= '9') result += s[i] - '0';
		}
		System.out.println(result);
	}
}