# This is a sample Python script.

# Press Shift+F10 to execute it or replace it with your code.
# Press Double Shift to search everywhere for classes, files, tool windows, actions, and settings.

def journals(s):
    seeking = True
    prev = s[0]
    res = 0
    for i in range(1, len(s)):
        if seeking:
            if prev == s[i]:
                seeking = False
            else:
                prev = s[i]
        else:
            if prev == s[i]:
                seeking = True
                res += 1
            else:
                prev = s[i]
    if not seeking:
        res += 1
    return res

# Press the green button in the gutter to run the script.
if __name__ == '__main__':
    print(journals(input()))




# See PyCharm help at https://www.jetbrains.com/help/pycharm/