#ifndef LOCAL
#pragma GCC optimize("O3")
#endif
#include <bits/stdc++.h>
using namespace std;
#define sim template <class c
#define mor > muu & operator<<(
#define ris return *this
#define eni(r) sim> typename enable_if <1 r sizeof(dud<c>(0)),muu&>::type operator<<(c g) {
sim> struct rge {c b,e ;};
sim> rge<c> range(c i, c j) {return rge<c>{i, j};}
sim> auto dud(c *r)-> decltype(cerr << *r);
sim> char dud(...);
struct muu {
	#ifdef LOCAL
	stringstream a;
	~muu() {cerr << a.str() << endl;}
	eni(<) a << boolalpha << g; ris;}
	eni(==) ris << range(begin(g), end(g));}
	sim, class m mor pair<m,c> r) {ris << "(" << r.first << ", " << r.second << ")";}
	sim mor rge<c> u) {
		a << "[";
		for (c i = u.b; i != u.e; ++i)
			*this << ", " + 2 * (i == u.b) << *i;
		ris << "]";
	}
	#else
	sim mor const c&) {ris;}
	#endif
	muu & operator()(){ris;}
};
#define debug (muu() << __FUNCTION__ << "#" << __LINE__ << ": ")
#define imie(r) "[" #r ": " << (r) << "] "
#define imask(r) "[" #r ": " << bitset<8 * sizeof(r)>(r) << "] "
#define arr(a, i) "[" #a imie(i) ": " << a[i] << "] "
#define arr2(a, i, j) "[" #a imie(i) imie(j) ": " << a[i][j] << "] "

using ll=long long;
const int nax=1000*1007;

char wcz[nax];

ll cel=1;

int wyn=6;

void rek(ll mas, int v)
{
	if (v>=wyn)
		return;
	if (mas==cel)
	{
		wyn=v;
		return;
	}
	if (v+1>=wyn)
		return;
	for (int i=1; i<=39; i++)
		rek(mas|(mas>>i), v+1);
}

int main()
{
	scanf("%s", wcz);
	if (wcz[0]=='0')
	{
		printf("-1\n");
		return 0;
	}
	ll sta=0;
	for (int i=0; wcz[i]; i++)
	{
		sta=(sta*2+wcz[i]-'0');
		cel*=2;
	}
	cel--;
	cerr << sta << " " << cel << endl;
	rek(sta, 0);
	printf("%d\n", wyn);
	return 0;
}