import java.util.Scanner;

public class Main {
	public static void main(String args[]) {

		Scanner sc = new Scanner(System.in);

		int a = Integer.parseInt(sc.next());
		int count = 0;
		
		if(a / 100 == 1) {
			count++;
			a -= 100;
		}
		
		
		if(a / 10 == 1) {
			count++;
			a -= 10;
		}
		
		if(a / 1 == 1) {
			count++;
		}
		System.out.println(count);

		sc.close();
	}
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz