#!/usr/bin/python3


line = list(input())
days = 0

while not all(map(lambda char: char == "1", line)):
    day_added = False
    new_line = line[:]
    for i in range(len(line)):
        if line[i] == "1":
            if i > 0:
                day_added = day_added or line[i-1] == "0"
                new_line[i-1] = "1"
            if i < len(line)-1:
                day_added = day_added or line[i+1] == "0"
                new_line[i+1] = "1"
    days += int(day_added)
    line = new_line
    print(line)

print(days)