s = list(input())
pre = s.pop(-1)
cnt = 1
f = 0
while len(s) >= 2:
    now = s.pop(-1)
    if f == 1:
        f = 0
    elif now == pre:
        s.pop(-1)
        f = 1
    else:
        pass
    cnt += 1
    pre = now
if len(s) == 1 and pre != s.pop(-1) or f == 1:
    cnt += 1
print(cnt)