import sys
input = sys.stdin.readline

S=input().strip()

ANS=0

for i in range(len(S)-2):
    X=S[i:i+3]

    if X[0]==X[1] and X[1]!=X[2]:
        ANS+=1
    elif X[1]==X[2] and X[0]!=X[1]:
        ANS+=1

print(ANS)