S = input()
ans = 0

if len(S) < 3:
    print(ans)
    exit()

for i in range(len(S)-2):
    s = S[i:i+3]
    if (s[0] == s[1] or s[1] == s[2]) and not(s[0] == s[1] and s[1] == s[2]):
        ans += 1
print(ans)