#include<iostream>
#include<string>
#include<algorithm>
#include<cctype>
#include<set>
#include<bitset>
#include<math.h>
#include<map>
#include<queue>
#include<iomanip>
using namespace std;

int main(){
    int cnt = 0;
    string a, b, c;
    cin >> c;
    for (int i = 0; i < c.size()-1; i++){
        a = c.substr(0, i+1);
        b = c.substr(i+1);
        if (!(b[0] == '0')) cnt++;
    }
    cout << cnt << endl;
}