import java.util.Scanner;

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

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