#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a; i<b; i++)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define debug printf

typedef long long ll;
typedef pair<int, int> pii;

const int duzo = 45;
char s[duzo];

int main()
{
	cin >> s;
	ll maska = 0;
	if(s[0] == '0') {
		cout << -1;
		return 0;
	}
	int dl = strlen(s);
	for(int i = 0; i < dl; ++i) {
		maska *= 2ll;
		if(s[i] == '1') maska += 1ll;
	}
	ll oczek = (1ll<<dl) - 1ll;
	if(maska == oczek) {
		cout << 0;
		return 0;
	}
	int przes = min(20, dl - 1);
	int nn = 50;
	for(int i = 0, ss = 1<<przes; i < ss; ++i) {
		ll wyn = maska;
		for(int l = 0; l < przes; ++l) {
			if(i&(1<<l)) wyn |= (wyn>>(l + 1));
		}
		if(wyn == oczek) nn = min(nn, __builtin_popcount(i));
	}
	cout << nn;
	return 0;
}