#include <iostream>
#include <cstdio>
using namespace std;

int test( string &s )
{
    int result = 0;
    for ( int i = 0; i < s.size(); ++i )
    {
        if ( s[i] == '1' ) result++;
    }
    return result;
}

int answer = 1000;

void fun( string &s, int q = 0 )
{
    if ( q == 7 ) return;

    if ( test( s ) == s.size() )
    {
        answer = min( q, answer );
        return;
    }

    //cout << "\t" << q << endl;
    string h;
    for ( int i = 1; i < s.size(); ++i )
    {
        h = s;
        for ( int j = 0; j+i < h.size(); ++j )
        {
            //cout << j << endl;
            if ( s[j] == '1' ) h[j+i]='1';
        }
        if ( test( h ) != test(s) )
            fun( h, q + 1 );
    }
}

int main()
{
    string s;
    cin >> s;

    if ( s[0] == '0' )
    {
        cout << "-1\n";
        return 0;
    }

    fun( s );
    cout << answer << endl;
}