#include <bits/stdc++.h>

using namespace std;

#define ll long long
#define ull unsigned long long

ull pls(char* arr) {
	ull res = 0;
	for(ull i = 0; i < strlen(arr); i++) {
		res *= 2;
		res += arr[i] - '0';
	}
	return res;
}

char arr[420];

int main() {
	cin >> arr;
	
	
	if(arr[0] == '0') {
		cout << "-1\n";
		return 0;
	}
	
	
	ull bm = pls(arr);
	
	unordered_set<ull> s{};
	s.insert(bm);
	queue<ull> oq{};
	queue<ull> nq{};
	oq.push(bm);
	
	ull steps = 1;
	ull len = strlen(arr);
	ull end = ((ull)1 << len) - 1;
	while(true) {
		if(oq.empty()) {
			swap(oq, nq);
			steps++;
			//if(oq.empty()) return 1;
			//cout << "steps:" << steps << endl;
		}
		
		bm = oq.front();
		oq.pop();
		//cout << bm << endl;
		
		if(bm == end) break;
		
		for(ull i = 0; i <= len; i++) {
			ull nw = bm | (bm >> i);
			//cout << "try:" << nw << endl;
			if(nw != bm && s.find(nw) == s.end()) {
				//cout << "insert:" << nw << endl;
				s.insert(nw);
				nq.push(nw);
			}
		}
	}
	
	cout << (steps-1) << endl;
	
	return 0;
}