#include <iostream>
#include <algorithm>
#include <iterator>
#include <cmath>
#include <ctime>
#include <vector>
#include <stack>
#include <deque>
#include <queue>
#include <set>
#include <map>
#include <stack>
#include <string>
#include <random>
#include <numeric>
#include <unordered_set>

typedef long long ll;
typedef long double lb;

#define fast ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define file_in freopen("input.txt", "r", stdin);
#define file_in_out freopen("inverse.in", "r", stdin); freopen("inverse.out", "w", stdout);
#define mp make_pair
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second

using namespace std;

template<typename T>
istream& operator>>(istream &in, vector<T> &v) {
	for (auto &it : v) {
		in >> it;
	}
	return in;
}

template<typename T>
ostream& operator<<(ostream &out, vector<T> &v) {
	if (!v.empty()) {
		out << v.front();
		for (int i = 1; i < v.size(); ++i) {
			out << " " << v[i];
		}
	}
	return out;
}

int main()
{
	fast
//	file_in
//	file_in_out

	string s;
	cin >> s;
	int ans = 0;
	for (int i = 0; i < s.size() / 2; ++i) {
		if (s[i] != '0') {
			++ans;
		}
	}

	if (s.size() % 2 == 0) {
		for (int i = s.size() / 2; i < s.size(); ++i) {
			if (s[i] < s[i - s.size() / 2]) {
				--ans;
				break;
			} else if (s[i] > s[i - s.size() / 2]) {
				break;
			}
		}
	}
	cout << ans;
    return 0;
}