#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
const int N = 1e5 + 3;
int T;
int n, num;
const int inf = 0x3f3f3f3f;

void work(){
	string s;cin >> s;
	while(s.back() == '0') s.pop_back();
	reverse(s.begin(),s.end());
	while(s.back() == '0') s.pop_back();
	int n = s.size();
	if(n == 0) {
		cout << "0\n";
		return;
	}
	auto calc = [&] () {
		vector <int> f(n);
		f[0] = 0;
		int pre = 0,zero = 0,cnt = 0;
		for(int i = 0;i < n;i++) {
			int j = i;
			f[i] = min(cnt,f[pre] + zero);
			cnt += 1;
			while(j + 1 < n && s[j + 1] == '1') {
				j += 1;
				f[j] = f[i];
				cnt += 1;
			} 
			pre = j;
			zero = 0;
			while(j + 1 < n && s[j + 1] == '0') {
				zero += 1;
				j += 1;
				f[j] = f[i];
			}
//			cout << cnt << ' ' << zero << ' ' << i << ' ' << j << '\n';
			i = j;
		}
//		cout << s << '\n';
//		for(auto &x : f) cout << x << ' ';
//		cout << '\n';
		return f;
	};
	auto f = calc();
	reverse(s.begin(),s.end());
	auto g = calc();
	reverse(g.begin(),g.end());
	reverse(s.begin(),s.end());
	int ans = inf;
	for(int i = 0;i < n;i++) if(s[i] == '1') ans = min(ans,f[i] + g[i]);
	cout << ans << '\n';
}


int main(){
//	freopen("test.txt", "r", stdin);
	ios::sync_with_stdio(false);
	cin.tie(0);
//	cin >> T;
//	while(T--){
		work();
//	}	
	return 0;
}