#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n-1); i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define endl "\n"
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	string s; cin >> s;
	int n = s.size();
	vector<vector<bool>>sdp(n + 1, vector<bool>(n + 1, false));
	rep(i, n + 1)sdp[i][i] = true;
	rep(i, n)sdp[i][i + 1] = true;
	rep2(i, 2, n + 1) {//sz
		rep(l, n) {
			int r = l + i;
			if (r > n)break;
			if ((s[l] == s[r - 1]) && sdp[l + 1][r - 1]) sdp[l][r] = true;
		}
	}
	vector<int>dp(n + 1, -INF);
	dp[0] = INF;
	rep(i, n)rep(j, i + 1) {
		if (!sdp[j][i + 1])continue;
		chmax(dp[i + 1], min(dp[j], i + 1 - j));
	}
	cout << dp[n] << endl;
	return 0;
}