#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i=0; i<n; i++)
#define pb push_back
typedef long long ll;

vector<int> manacher(string s) {
    int n = s.size();
    vector<int> res(n);
    int i = 0;
    int j = 0;
    while (i<n) {
        while (i-j>=0 && i+j<n && s[i-j]==s[i+j]) j++;
        res[i] = j;
        int k = 1;
        while (i-k>=0 && k+res[i-k]<j) {
            res[i+k] = res[i-k];
            k += 1;
        }
        i += k;
        j -= k;
    }
    return res;
}

int main() {
    cin.tie(0); ios::sync_with_stdio(false);
    
    string S; cin >> S;
    string T;
    for (char c : S) {
        T += '&';
        T += c;
    }
    vector<int> mana = manacher(T);
    int n = S.size();
    bool is_pal[n][n+1];
    rep(l, n) for (int r=l+1; r<=n; r++) {
        int center = l+r;
        is_pal[l][r] = 2*r-1<center+mana[center];
    }
    
    int ok = 1;
    int ng = n+10;
    while (abs(ok-ng)>1) {
        int mid = (ok+ng)/2;
        bool dp[n+1];
        fill(dp, dp+n+1, false);
        dp[0] = true;
        rep(i, n) {
            if (!dp[i]) continue;
            for (int j=i+mid; j<=n; j++) if (is_pal[i][j]) dp[j] = true;
        }
        if (dp[n]) ok = mid;
        else ng = mid;
    }
    
    cout << ok << endl;
}