S=input()
l=len(S)
def solve(s,h):
    if h==1:
        return 1
    elif h==2:
        if s[0]==s[1]:
            return 1
        else:
            return 2
    elif h==0:
        return 0
    else:
        if s[h-1]==s[h-2]:
            return solve(s,h-3)+2
        else:
            return solve(s,h-1)+1
print(solve(S,l))
        