
java
import java.util.Scanner;
public class DemoTest11 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
while (sc.hasNext()) {
char[] chars = sc.nextLine().toCharArray();
int i = 0,res = 0;
while(i<chars.length){
if(chars[i]== '0'){
// i=0时,左边为空,无需判断,或者i!=0时,i的前一位为0
boolean left = i==0|| chars[i-1]=='0';
// i=chars.length-1时,右边为空,无需判断,或者i!=chars.length-1时,i的后一位为0
boolean right = i==chars.length-1 || chars[i+1]=='0';
if(left && right){
chars[i]='1';//如果可以坐人,填充为1
res++;
}
}
i++;
}
System.out.println(res);
}
}
}