import java.util.Scanner;
public class Main
{   
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int a = x/100;
        int b = x/10%10;
        int c = x%10;
        System.out.println(a+b+c); 
    }
}
/**************************************************************
	Problem: 1733
	User: admin
	Language: Java
	Result: Accepted
	Time:768 ms
	Memory:39872 kb
****************************************************************/