# This is a sample Python script.
from functools import reduce


# 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 main():
    # Use a breakpoint in the code line below to debug your script.
    sentence = input()
    a = find_splits_for_sentence(sentence)
    arr2 = []
    start = 0

    print(len(a)//2 + len(a) % 2)
    # for sequence in a:
    #     arr2.append(sentence[start * 2:sequence * 2])
    #     start = sequence
    # arr2.append(sentence[start * 2:])
    # for i in range(len(arr2)):
    #     swap(i, arr2.copy())


def swap(pair, arr):
    arr[pair] = reverse(arr[pair])
    seq = reduce(lambda x,y: x+y, arr)
    new_splits = find_splits_for_sentence(seq)
    pass


def reverse(str):
    new_str = ""
    for i in range(len(str) - 1, -1, -1):
        new_str += str[i]
    return new_str


def find_splits_for_sentence(sentence):
    a = []
    end = 0
    previous = ""
    for ind in range(0, len(sentence), 2):
        if ind > 0:
            end += 1
            if (sentence[ind], sentence[ind + 1]) != previous:
                a.append(end)
        previous = (sentence[ind], sentence[ind + 1])
    return a


# Press the green button in the gutter to run the script.
if __name__ == '__main__':
    main()
# See PyCharm help at https://www.jetbrains.com/help/pycharm/