import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s1 = scanner.next();
        s1 = s1.replaceAll("0","");
        System.out.println(s1.length());
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s1 = scanner.next();
        s1 = s1.replaceAll("0","");
        System.out.println(s1.length());
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s1 = scanner.next();
        s1 = s1.replaceAll("0","");
        System.out.println(s1.length());
    } main {
        Scanner scanner = new Scanner(System.in);
        String s1 = scanner.next();
        s1 = s1.replaceAll("0","");
        System.out.println(s1.length());
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) String s1 = scanner.next(); s1 scanner.next() scanner.next scanner s1 = s1.replaceAll("0","") s1 s1.replaceAll("0","") s1.replaceAll s1 "0" "" System.out.println(s1.length()) System.out.println System.out System System.out s1.length() s1.length s1 String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s1 = scanner.next();
        s1 = s1.replaceAll("0","");
        System.out.println(s1.length());
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s1 = scanner.next();
        s1 = s1.replaceAll("0","");
        System.out.println(s1.length());
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String s1 = scanner.next();
        s1 = s1.replaceAll("0","");
        System.out.println(s1.length());
    }
}