S=input()
nx,ny=0,0
s=len(S)
D=[(0,0)]
for i in range(s):
    if i%2==0:
        if nx%3==0:
            if S[i]=='a':
                ny-=1 
            elif S[i]=='b':
                nx+=1 
            else:
                nx-=1 
        elif nx%3==2:
            if S[i]=='a':
                nx-=1 
            elif S[i]=='b':
                ny-=1 
            else:
                nx+=1 
        else:
            if S[i]=='a':
                nx+=1 
            elif S[i]=='b':
                nx-=1 
            else:
                ny-=1
    else:
        if nx%3==1:
            if S[i]=='a':
                nx+=1 
            elif S[i]=='b':
                nx-=1 
            else:
                ny+=1 
        elif nx%3==0:
            if S[i]=='a':
                ny+=1 
            elif S[i]=='b':
                nx+=1 
            else:
                nx-=1 
        else:
            if S[i]=='a':
                nx-=1 
            elif S[i]=='b':
                ny+=1 
            else:
                nx+=1
    D.append((nx,ny))

print(len(set(D)))