#include <iostream>
#include <string>
#include <bitset>

using namespace std;

using ll = unsigned long long;

int N;
int er = 10000000;
int xe;

void megold(int x, int min, int o, int l)
{
    if(l >= er || o >= N)
        return;
    if(x == xe)
    {
        er = l;
        return;
    }
    for(int i = min; i < N; i++)
    {
        megold(x | (x >> i), i, o + i, l + 1);
    }
}

int main()
{
    string s;
    cin >> s;
    bitset<40> b(s);
    ll x = b.to_ullong();
    N = s.size();
    xe = (1ull << N) - 1;
    if((x & (1ull << (N - 1))) == 0)
    {
        cout << "-1\n";
        return 0;
    }
    megold(x, 1, 0, 0);
    cout << er << "\n";
}