#input of int(split by space)
def get_i()
  return gets.chomp.split(" ").map(&:to_i)
end
#input of float(split by space)
def get_f()
  return gets.chomp.split(" ").map(&:to_f)
end
#input of string(split by space)
def get()
  return gets.chomp.split(" ")
end
#input of string(split per one character)
def get_nsp()
  return gets.chomp.split("")
end
#yes or no decision
def yn_judge(bool,y="Yes",n="No")
  return bool ? y : n 
end
#create of array
def array(size1,init=nil,size2=-1)
  if size2==-1
    return Array.new(size1){init}
  else
    return Array.new(size2){Array.new(size1){init}}
  end
end

def max(a,b)
    return a>b ? a : b
end

def min(a,b)
    return a>b ? b : a
end

INF=Float::INFINITY

S=get_nsp
N=S.size
dp=array(S.size,0)
dp[0]=1
if S[0]==S[1]
    dp[1]=1
else
    dp[1]=2
end

if S[0]!=S[1] and S[1]!=S[2]
    dp[2]=3
else
    dp[2]=2
end
3.upto(N-1) do|i|
  if S[i-1]==S[i]
    dp[i]=dp[i-3]+2
  else
      dp[i]=dp[i-2]+1
  end
end
puts dp[N-1]