#include<iostream>
#include<string>
using namespace std;
int main() {
	char s[1010];
	cin >> s;
	int cnt = 0;
	for (int i = 0; i < 1010; i++) {
		if (s[i] == '0')
			cnt++;
		else if (s[i] == 0)
			break;

			cout << cnt - 8 <<endl;
			//cin >> s;
			return 0;		
	}
return 0;
}