import java.util.*;

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

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