#include <bitset>
#include <cctype>
#include <iostream>

using namespace std;

typedef uint64_t u64;

int ss;

int det(u64 n){
	int min=41,h;
	int l = __builtin_clzll(~n);
	//cout << l << endl;
	if (__builtin_popcountll(n) == ss)
		return 0;
	for(int i = 1; i <= l; i++) {
		h = det(((n | n >> i) >> (64 - ss)) << (64 - ss));
		if (h < min) min = h;
		if (min == 0) break;
	}
	return min + 1;
}

int main(){
	std::ios_base::sync_with_stdio(false);
	string s;
	cin >> s;
	if (s[0] == '0')
		cout << -1 << '\n';
	else {
		ss = s.size();
		bitset<40> bs(ss);
		int n = det(bs.to_ullong() << (64 - ss));
		cout << n << '\n';
	}
}