#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

template <class T>
vector<int> Manacher(const T& s) {
  const int n = s.size();
  vector<int> res(n);
  for (int i = 0, r = 1; i < n;) {
    int l = 2 * i - r;
    while (0 <= l && r < n && s[l] == s[r]) l--, r++;
    res[i] = r - i;
    if (++i != r) {
      int j = i - 2;
      while (i + res[j] < r) res[i++] = res[j--];
    }
  }
  return res;
}

template <class T>
vector<int> Manacher_cursor(const T& s) {
  const int n = s.size();
  vector<int> res(n + 1);
  for (int i = 1, r = 1; i < n;) {
    int l = 2 * i - r;
    while (l && r < n && s[l - 1] == s[r]) l--, r++;
    res[i] = r - i;
    if (i++ != r) {
      int j = i - 2;
      while (i + res[j] < r) res[i++] = res[j--];
    } else {
      r = i;
    }
  }
  return res;
}

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  string s;
  cin >> s;
  int n = s.size();
  auto me = Manacher(s);
  auto mc = Manacher_cursor(s);
  int l = 1, r = n + 1;
  vector<char> dp;
  while(r - l > 1) {
    int c = (l + r) / 2;
    dp.assign(n + 1, false);
    dp[0] = true;
    rep(i, n) if (dp[i]) {
      for (int j = i + c; j <= n; j++) {
        int len = j - i;
        if (len & 1) {
          int p = (i + j - 1) / 2;
          int rad = j - p;
          if (me[p] >= rad) dp[j] = true;
        } else {
          int p = (i + j) / 2;
          int rad = p - i;
          if (mc[p] >= rad) dp[j] = true;
        }
      }
    }
    (dp[n] ? l : r) = c;
  }
  cout << l << '\n';
}