import java.util.*;
class Test38{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		String str = sc.next();
		char[] c = str.toCharArray();
		int sum = 0;
		
		for(int i=0; i<c.length; i++){
			if(c[i]=='0'||c[i]=='1'||c[i]=='2'||c[i]=='3'||c[i]=='4'||c[i]=='5'||c[i]=='6'||c[i]=='7'||c[i]=='8'||c[i]=='9'){
				sum += (int)(c[i])-48;
			}
		}
		
		System.out.println(sum);
	}
}