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