#pragma GCC optimize("Ofast","unroll-loops")

#include <bits/stdc++.h>

#define rep(i, j, k) for (int i = (j); i <= (k); ++i)
#define per(i, j, k) for (int i = (j); i >= (k); --i)
#define SZ(v) int((v).size())
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second
using ll = long long;
using pii = std::pair<int, int>;
using pll = std::pair<ll, ll>;

template<class T>inline void chkmn(T &x, T y) { if (y < x) x = y; }
template<class T>inline void chkmx(T &x, T y) { if (y > x) x = y; }

using namespace std;

const int maxn = 450010;
mt19937 rnd(random_device{}());

string s, t;
int n, m, a[maxn], b[maxn], to[maxn][2], ot[maxn][2];
vector<pii> val;

int main() {
  cin.tie(nullptr) -> ios::sync_with_stdio(false);
  s = "a"s, t = "b"s;
  while (SZ(t) < 450000) {
    string p = s + t;
    t = s, s = p;
  }
  t.resize(450000);
  cin >> s;
  n = SZ(s), m = SZ(t);
  rep (i, 1, n) a[i] = s[i - 1] - 'a';
  rep (i, 1, m) b[i] = t[i - 1] - 'a';
  vector<int> vec;
  rep (i, 1, m - 1) {
    vec.emplace_back(b[i]);
    if (b[i] == b[i + 1] && b[i] == 1) vec.emplace_back(0);
  }
  vec.emplace_back(b[m]);
  m = SZ(vec);
  rep (i, 1, m) b[i] = vec[i - 1];
  to[m + 1][0] = to[m + 1][1] = m + 1;
  per (i, m, 1) {
    to[i][0] = to[i + 1][0], to[i][1] = to[i + 1][1];
    if (i != m) to[i][b[i + 1]] = i + 1;
  }
  ot[0][0] = ot[0][1] = 0;
  rep (i, 1, m) {
    ot[i][0] = ot[i - 1][0], ot[i][1] = ot[i - 1][1];
    if (i != 1) ot[i][b[i - 1]] = i - 1;
  }
  if (n <= 800) {
    rep (i, 1, m - n + 1) if (a[1] == b[i]) {
      int pos = i;
      rep (j, 2, min(n, 300)) {
        pos = to[pos][a[j]];
        if (pos > m) break;
      }
      if (pos > m) continue;
      val.emplace_back(pos - i, i);
    }
    sort(ALL(val));
    int ans = 1e9;
    for (auto [len, i] : val) {
      if (clock() / CLOCKS_PER_SEC > 3.5) break;
      int pos = i;
      rep (j, 2, n) {
        pos = to[pos][a[j]];
        if (pos > m) break;
      }
      if (pos > m) continue;
      chkmn(ans, pos - i + 1);
    }
    cout << ans << '\n';
    return 0;
  }
  // int S = uniform_int_distribution<int>(1, n - 299)(rnd), T = S + 299;
  int S = 1, T = 800;
  rep (i, 1, m - 799) {
    if (b[i] != a[S]) continue;
    int pos = i;
    rep (j, S + 1, T) pos = to[pos][a[j]];
    if (pos <= m) val.emplace_back(pos - i, i);
  }
  sort(ALL(val));
  int ans = 1e9;
  for (auto [fool, i] : val) {
    if (1. * clock() / CLOCKS_PER_SEC >= 3.9) break;
    int R = i, L = i;
    rep (j, S + 1, n) R = to[R][a[j]];
    per (j, S - 1, 1) L = ot[L][a[j]];
    if (R <= m && L >= 1) chkmn(ans, R - L + 1);
  }
  cout << ans << '\n';
}