import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner a = new Scanner(System.in);
        int s1 = a.nextInt();
        a.close();
        if (s1 - 111 == 0) {
            System.out.print("3");
        }
        if (s1 - 110 == 0) {
            System.out.print("2");
        }
        if (s1 - 101 == 0) {
            System.out.print("2");
        }
        if (s1 - 100 == 0) {
            System.out.print("1");
        }
        if (s1 - 11 == 0) {
            System.out.print("2");
        }
        if (s1 - 10 == 0) {
            System.out.print("1");
        }
        if (s1 - 1 == 0) {
            System.out.print("1");
        }
        if (s1 - 0 == 0) {
            System.out.print("0");
        }
    }
}

/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