import sys, math
sys.set_int_max_str_digits(0)

S = input()
N = len(S)
ans = 0
for i in range(N - 2):
    if S[i] == S[i + 1] and S[i + 1] != S[i + 2]:
        ans += 1
S = S[::-1]
for i in range(N - 2):
    if S[i] == S[i + 1] and S[i + 1] != S[i + 2]:
        ans += 1
print(ans)