if __name__ == '__main__': input = input() signs = [] for char in input: signs.append(char) result = 0 mistake = False i = 0 while i < len(signs)-1: if signs[i] == signs[i+1]: j = i+1 while signs[j] == signs[i]: j += 1 var = signs[i + 1:j + 1][::-1] signs[i+1:j+1] = var result += 1 i += 1 print(result)