package 刷题.入门;

import java.util.Scanner;

public class 硬币翻转 {
	public static void main(String[] args) {
		Scanner scanner=new Scanner(System.in);
		String nextLine = scanner.nextLine();
		char[] charArray = nextLine.toCharArray();
		int steps=0;
		int i;
		int j;
		for ( i = charArray.length-1; i >= 0; i--) {
			if (charArray[i]=='0') {
				for ( j = 0; j <=i; j++) {
					if (charArray[j]=='0') {
						charArray[j]='1';
					}else {
						charArray[j]='0';
					}
				}
				steps++;
			}	
		}
		System.out.println(steps);
	}
}