using System;

public class Test {
	public static void Main(string[] args) {
		char[] chars = Console.ReadLine().ToCharArray();
		int sum = 0;
		for (int i = 0; i < chars.Length; i++) {
			int value = 0;
			if (int.TryParse(chars[i].ToString(), out value)) {
				sum += value;
			}
		}
		Console.WriteLine(sum);
	}
}