#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 50;
char B[maxn];
int main()
{
	scanf("%s", B);
	int len = strlen(B);
	ll x = 0;
	for(int i = 0; i < len; ++i)
	{
		x *= 2;
		if(B[i] == '1')
			x += 1;

	}
	if(x == 0)
	{
		puts("-1");
		return 0;
	}
	int res = 1000;
	for(int i = 0; i < (1 << 21); ++i)
	{
		ll y = x;
		int d = 0;
		for(int j = 0; j < 25; ++j)
		{
			if(i & (1 << j))
			{
				y |= y >> (j + 1);
				++d;
			}
		}
		if(y + 1 == (1ll << len))
			res = min(res, d);
		
	}
	if(res == 1000)
	{
		puts("-1");
		return 0;
	}
	
	printf("%d\n", res);
}