#include <map>
#include <set>
#include <array>
#include <cmath>
#include <deque>
#include <bitset>
#include <random>
#include <string>
#include <vector>
#include <cassert>
#include <complex>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#include <unordered_set>

using namespace std;

const int MAXN = 2e5, MAXLN = 100;
int rgh[MAXLN][MAXN];
int lft[MAXLN][MAXN];
int len[MAXLN];


int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);

  len[0] = len[1] = 1;
  for (int i = 2; i < MAXLN; ++i) {
    len[i] = len[i - 1] + len[i - 2];
    if (len[i] >= (int)1e6) break;
  }

  string t;
  cin >> t;
  int n = t.size();
  if (n == 1) {
    cout << "1\n";
    return 0;
  }

  for (int i = 0; i < n; ++i) {
    rgh[0][i] = i + (t[i] == 'b');
    rgh[1][i] = i + (t[i] == 'a');
  }
  for (int i = 0; i < MAXLN; ++i) {
    rgh[i][n] = n;
  }
  int lvl;
  for (lvl = 2; rgh[lvl - 1][0] < n; ++lvl) {
    for (int i = 0; i < n; ++i) {
      rgh[lvl][i] = rgh[lvl - 2][rgh[lvl - 1][i]];
    }
  }

  int maxr = lvl;

  auto go_right = [&](int i) {
    int ans = 0;
    for (int lvl = maxr - 1; lvl >= 1; --lvl) {
      if (rgh[lvl][i] < n) {
        ans += len[lvl];
        i = rgh[lvl][i];
      }
    }
    return ans + 1;
  };

  for (int i = 1; i <= n; ++i) {
    lft[0][i] = i - (t[i - 1] == 'b');
    lft[1][i] = i - (t[i - 1] == 'a');
  }
  for (int i = 0; i < MAXLN; ++i) {
    lft[i][0] = 0;
  }
  for (lvl = 2; lft[lvl - 2][n] > 0; ++lvl) {
    for (int i = 1; i <= n; ++i) {
      lft[lvl][i] = lft[lvl - 1][lft[lvl - 2][i]];
    }
  }

  int maxl = lvl;

  auto go_left = [&](int i, int r) {
    int start = maxl - 1;
    if (start % 2 != r) --start;
    int ans = 0;
    for (int lvl = start; lvl >= 0; --lvl) {
      if (lft[lvl][i] > 0) {
        ans += len[lvl];
        i = lft[lvl][i];
      } else {
        --lvl;
      }
    }
    return ans + 1;
  };

  int ans = 3 * n;

  for (int i = 1; i < n; ++i) {
    for (int r = 0; r < 2; ++r) {
      int p = go_left(i, r);
      int q = go_right(i);
      ans = min(ans, p + q);
    }
  }
  cout << ans << "\n";

  
  return 0;
}