from sys import stdin

mem = {}
total_len = -1
current_min = 50
result = -1

def solve(line, relocations):
	#print('depth', relocations)
	global mem, total_len, current_min, result
	if relocations > total_len:
		return total_len
	elif relocations == current_min:
		return current_min
	elif line in mem:
		return mem[line]
	elif line == result:
		return relocations
	else:
		shifts = [0] * total_len
		min_relocations =  50
		for i in range(total_len):
			if (1 << i) & line == 0:
				for j in range(i+1, total_len):
					if (1 << j) > 0:
						shifts[j-i] += 1
		for i, shift in enumerate(shifts):
			if shift > 0:
				new_line = line | line>>i
				min_relocations = min(min_relocations, solve(new_line, relocations + 1))
				if relocations == 0:
					current_min = min_relocations
		mem[line] = min_relocations
		
		return min_relocations

#print('starting')
line = stdin.readline().strip()
if line[0] == '0':
	print(-1)
else:
	total_len = len(line)
	result = (1 << total_len) - 1
	num = 0
	for char in line:
		if char == '1':
			num += 1
		num*=2
	num = int(num/2)
	print(solve(num, 0))