
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		System.out.println(str.replaceAll("0", "").length());
		sc.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		System.out.println(str.replaceAll("0", "").length());
		sc.close();
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		System.out.println(str.replaceAll("0", "").length());
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		System.out.println(str.replaceAll("0", "").length());
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) String str = sc.next(); str sc.next() sc.next sc System.out.println(str.replaceAll("0", "").length()) System.out.println System.out System System.out str.replaceAll("0", "").length() str.replaceAll("0", "").length str.replaceAll("0", "") str.replaceAll str "0" "" sc.close() sc.close sc String[] args args public class Main {

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		System.out.println(str.replaceAll("0", "").length());
		sc.close();
	}
} public class Main {

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		System.out.println(str.replaceAll("0", "").length());
		sc.close();
	}
} Main

import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		String str = sc.next();
		System.out.println(str.replaceAll("0", "").length());
		sc.close();
	}
}