import sys
sys.setrecursionlimit(2000)
input = sys.stdin.readline
#無限大
INF = (1 << 61) - 1
#4つのマスチェック用
four_step = [(0, 1), (1, 0), (-1, 0), (0, -1)]
def chmmin(a, b):
    if a > b:
        a = b
        return True
    else:
        return False
def chmax(a, b):
    if a < b:
        a = b
        return True
    else:
        return False
S = list(str(input()))
r = 0
l = 1
len_s = len(S)
ans = 0
for i in range(len_s):
    kind = 1
    for j in range(0, 2):
        if S[r+j] != S[r+j+1]:
            kind += 1
    if kind == 2:
        ans += 1
        #print(S[r]+S[r+1]+S[r+2])
    r += 1
    if r >= len_s - 3:
        break
print(ans)