#include <iostream>
#include <vector>
#include <cstdlib>
#include <cstdio>
#include <set>
#include <string>
#include <cmath>
using namespace std;
using LL = long long;

int b;
LL goal;
int mindepth;

void megold( LL szam, int depth) {
	if (depth >= mindepth)
		return;
	if ( (szam & goal) == goal) {
		mindepth = depth;
		return;
	}
	
	for (int i = 1; i <= b/2; i++){
		//cout << "eltol " << i << "-vel ";
		//printf("%x %x\n", szam, (szam<<i)); 
		megold( szam | (szam << i) , depth+1 );
	}
	
	
}

int main() {
	
	string s;
	cin>>s;
	
	if (s[0] == '0') {
		cout << -1 << endl;
		return 0;
	}
	
	b = s.length();
	goal = (1LL<<(b)) -1;
	
	//cout << "goal: " << goal << endl;
	
	mindepth = ceil( log2( b ) );
	
	//cout << " min: " << mindepth << endl;
	
	LL num = 0;
	
	for (int i = 0; i < b; i++){
		num |= (LL(s[i]-'0') << i);
	}
	
	//cout << "num: " << num << endl;
	
	megold(num, 0);
	
	cout << mindepth << endl;
	
	
	return 0;
}