if __name__ == '__main__':
    input = input()
    signs = []
    for char in input:
        signs.append(char)

    result = 0
    mistake = False
    for i in range(0, len(signs)-1):
        if signs[i] == signs[i+1]:
            mistake = True
            for j in range(i+1, len(signs)-1):
                if signs[j] == signs[j + 1]:
                    result += 1
                    mistake = False
                    i = j+1
    if mistake:
        result += 1

    print(result)