#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <climits>
#include <map>
#include <queue>
#include <set>
#include <cstring>
#include <vector>

using namespace std;
typedef long long ll;

bool is_kaibun[5010][5010];
string S;
int memo[5010];
int N;

bool check(int l, int r) {
  int i = l;
  int j = r;

  while (i < j) {
    if (S[i] != S[j]) return false;

    ++i;
    --j;
  }

  return true;
}

int dfs(int l) {
  if (memo[l] != -1) {
    return memo[l];
  }
  if (l >= N) return 9999;

  int res = 1;

  for (int r = l; r < N; ++r) {
    if (not is_kaibun[l][r]) continue;

    int len = r - l + 1;
    res = max(res, min(len, dfs(r + 1)));
  }

  return memo[l] = res;
}

int main() {
  memset(is_kaibun, false, sizeof(is_kaibun));
  memset(memo, -1, sizeof(memo));

  cin >> S;
  N = S.size();
  for (int l = 0; l < N; ++l) {
    set<int> M;
    for (int r = l; r < N; ++r) {
      M.insert(S[r] - 'a');

      if (M.size() == 1) {
        is_kaibun[l][r] = true;
      } else {
        is_kaibun[l][r] = check(l, r);
      }
    }
  }

  cout << dfs(0) << endl;

  return 0;
}