using System;
using System.Linq;
using System.Collections.Generic;

namespace Contest
{
    class Program
    {
        static void Main(string[] args)
        {
            AGC037.A();
        }



        class AGC037
        {
            public static void A()
            {
                var S = Read.Str();
                var N = S.Length;
                var dp = new int[N + 1, 4];
                dp[0, 2] = dp[0, 3] = -1000000000;
                for(int i = 0; i < N; ++i)
                {
                    dp[i + 1, 0] = dp[i, 1] + 1; if (i > 0 && S[i] != S[i - 1]) { dp[i + 1, 0] = Math.Max(dp[i + 1, 0], dp[i, 0] + 1); }
                    dp[i + 1, 1] = dp[i, 2] + 1; if (i > 3 && (S[i] != S[i - 2] || S[i - 1] != S[i - 3])) { dp[i + 1, 1] = Math.Max(dp[i + 1, 1], dp[i, 3] + 1); }
                    dp[i + 1, 2] = dp[i, 0];
                    dp[i + 1, 3] = dp[i, 1];
                }
                Console.WriteLine(Math.Max(dp[N, 0], dp[N, 1]));
            }
            public static void C()
            {
                var N = Read.Int();
                var A = Read.IntN();
                var B = Read.IntN();
                SortedList<int, int> queue = new SortedList<int, int>();
                for(int i = 0; i < N; ++i)
                {
                    if (A[i] != B[i]) { queue.Add(B[i], i); }
                }
                long count = 0;
                while (queue.Count > 0)
                {
                    var max = queue.Last();
                    queue.RemoveAt(queue.Count - 1);
                    var i = max.Value;
                    var b = B[i];
                    var a = B[(i + N - 1) % N];
                    var c = B[(i + 1) % N];
                    if ((b - A[i]) % (a + c) == 0)
                    {
                        count += (b - A[i]) / (a + c);
                        B[i] = A[i];
                    }
                    else
                    {
                        var v = (b - A[i] - 1) / (a + c);
                        count += v;
                        B[i] -= v * (a + c);
                        if (v == 0 || A[i] > B[i]) { Console.WriteLine(-1); return; }
                        queue.Add(B[i], i);
                    }
                }
                Console.WriteLine(count);
            }
        }
        class Util
        {
        }

        static class Read
        {
            static Queue<string> queue = new Queue<string>();
            static void Enqueue() { var ss = Console.ReadLine().Split(' '); foreach (var s in ss) { queue.Enqueue(s); } }
            public static int Int() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt32(queue.Dequeue()); }
            public static long Long() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt64(queue.Dequeue()); }
            public static string Str() { if (queue.Count == 0) { Enqueue(); } return queue.Dequeue(); }
            public static int[] IntN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt32(s)).ToArray(); }
            public static long[] LongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt64(s)).ToArray(); }
            public static string[] StrN() { return Console.ReadLine().Split(' '); }
            public static Tuple<int, int>[] TupleInt(int n) { List<Tuple<int, int>> list = new List<Tuple<int, int>>(); for (int i = 0; i < n; ++i) { var ab = Read.IntN(); list.Add(new Tuple<int, int>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<long, long>[] TupleLong(int n) { List<Tuple<long, long>> list = new List<Tuple<long, long>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<long, long>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<string, string>[] TupleStr(int n) { List<Tuple<string, string>> list = new List<Tuple<string, string>>(); for (int i = 0; i < n; ++i) { var ab = Read.StrN(); list.Add(new Tuple<string, string>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<double, double>[] TupleDouble(int n) { List<Tuple<double, double>> list = new List<Tuple<double, double>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<double, double>(ab[0], ab[1])); } return list.ToArray(); }
            public static long[,] LongMatrix(int r, int c)
            {
                var mat = new long[r, c];
                for (int i = 0; i < r; ++i)
                {
                    var x = Read.LongN();
                    for (int j = 0; j < c; ++j)
                    {
                        mat[i, j] = x[j];
                    }
                }
                return mat;
            }
            public static Dictionary<int, HashSet<int>> AdjacencyList(int N, int M)
            {
                Dictionary<int, HashSet<int>> dict = new Dictionary<int, HashSet<int>>();
                for (int i = 0; i <= N; ++i)
                {
                    dict.Add(i, new HashSet<int>());
                }
                for (int i = 0; i < M; ++i)
                {
                    var ab = Read.IntN();
                    dict[ab[0]].Add(ab[1]);
                    dict[ab[1]].Add(ab[0]);
                }
                return dict;
            }
            public static Dictionary<int, Dictionary<int, long>> AdjacencyListWithWeight(int N, int M)
            {
                Dictionary<int, Dictionary<int, long>> dict = new Dictionary<int, Dictionary<int, long>>();
                for (int i = 0; i <= N; ++i)
                {
                    dict.Add(i, new Dictionary<int, long>());
                }
                for (int i = 0; i < M; ++i)
                {
                    var ab = Read.IntN();
                    dict[ab[0]].Add(ab[1], ab[2]);
                    dict[ab[1]].Add(ab[0], ab[2]);
                }
                return dict;
            }
        }
    }
}


Measured memory_bytes: 15712