# coding: utf-8
# Your code here!
import sys
read = sys.stdin.read
readline = sys.stdin.readline

#n, *a = map(int,read().split())

s = input()
n = len(s)
ans = 0
for i in range(1,n):
    s1 = s[:i]
    s2 = s[i:]
    if s2[0] != "0": ans += 1

print(ans)