from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right, insort
from itertools import permutations, combinations, groupby
from heapq import heappop, heappush
import math, sys
input = lambda: sys.stdin.readline().rstrip("\r\n")
def printl(li, sep=" "): print(sep.join(map(str, li)))
def yn(flag): print(Yes if flag else No)
_int = lambda x: int(x)-1
MOD = 998244353 #10**9+7
INF = 1<<60
Yes, No = "Yes", "No"

S = input()
def check(st):
    if st[0] == st[1] != st[2]: return True
    if st[0] != st[1] == st[2]: return True
    return False

ans = 0
for i in range(len(S)-3+1):
    ans += check(S[i:i+3])
print(ans)