s = str(input())
num = len(s)
dp = [[0,0] for i in range(n+1)]
for i in range(n):
  for j in [1,2]:
    for k in [1,2]:
      if i + k <= n:
        a = s[i-j:i]
        b = s[i:i+k]
        if a != b:
          dp[i+k][k-1] = max(dp[i+k][k-1],dp[i][j-1]+1)
print(max(dp[n]))