#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll z = 0;
int main() {
  string S;
  cin >> S;
  int K = S.size();
  vector<int> DP(K + 1, 0);
  DP[1] = 1;
  if (S[0] == S[1])
    DP[2] = 1;
  else
    DP[2] = 2;
  for (int i = 3; i <= K; i++) {
    if (S[i] != S[i - 1]) {
      DP[i] = DP[i - 1] + 1;
    } else
      DP[i] = DP[i - 3] + 2;
  }
  cout << DP[K] << endl;
}
