#include <iostream>

using namespace std;

void cnt_cif(int n, int &nr){
    if (n == 0)
    {
        nr = 0;
        return;
    }
    cnt_cif(n / 10, nr);
    if (n % 10 == 0)
        nr++;
}
int main(){
    int a, s;
    cin >> a;
    cnt_cif(a, s);
    cout << s;
    return 0;
}