#include <bits/stdc++.h>

using namespace std;

#define sz(x) ((int) (x).size())
typedef long long ll;
typedef long double ld;

typedef string str;

vector<vector<int>> manacher(str &s) {
  int n = sz(s);
  vector<vector<int>> p(2, vector<int>(n));
  for (int k = 0; k < 2; k++)
    for (int i = 0, l = 0, r = 0; i < n; i++) {
      p[k][i] = i < r ? min(r - i + !k, p[k][l + r - i + !k]) : 0;
      int L = i - p[k][i], R = i + p[k][i] - !k;
      while (L > 0 && R + 1 < n && s[L - 1] == s[R + 1])
        p[k][i]++, L--, R++;
      if (R > r)
        l = L, r = R;
    }
  return p;
}

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(12);
  string s;
  cin >> s;
  int n = sz(s);
  vector<vector<int>> m = manacher(s);
  vector<int> lp = {0}, rp = {n};
  int c = 0;
  for (int i = 1; i < n; i++)
    if (i - m[0][i] <= c)
      c = i, lp.push_back(i);
  c = n;
  for (int i = n - 1; i >= 1; i--)
    if (i + m[0][i] >= c)
      c = i, rp.push_back(i);
  int r = n;
  for (int i : lp) {
    while (rp.back() <= i)
      rp.pop_back();
    r = min(r, rp.back() - i);
  }
  cout << r << "\n";
}