#include <iostream>
using namespace std;

int main(){
	
	unsigned int input;
	unsigned int len = 0;
	unsigned int zero = 0;
	
	cin >> input;
	
	while (input!=0){
		
		input /= 10;
		len++;
		
		if(input % 10 == 0){
			
			zero++;
			
		}
		
	}
	
	cout << len - zero - 1 << endl;
	
	
	return 0;
}