#!/usr/bin/env python3

import numpy as np

signs = input().strip()
nums = [0] * (len(signs) // 2)

for i in range(0, len(signs), 2):
    if signs[i] == '+':
        nums[i // 2] = 1
    else:
        nums[i // 2] = -1

groups = [0, 0, 0]
last = 0

for i in nums:
    if i == -last:
        groups[last] += 1
    last = i
groups[last] += 1

print(min(groups[1], groups[2]))