#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < n; ++i)
#define rep3(i, l, n) for (int i = l; i < n; ++i)
#define chmax(a, b) a = (a >= b ? a : b)
#define chmin(a, b) a = (a <= b ? a : b)
#define out(a) cout << (a) << endl
#define outa(a, n) rep(_, n) cout << a[_] << " "; cout << endl
#define SZ(v) (int)v.size()
#define inf (int)(1e9+7)
#define abs(x) (x >= 0 ? x : -(x))

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    string s;
    cin >> s;
    // out(SZ(s));
    int ans = 0;
    rep(i, SZ(s)) {
        int c = 0;
        rep(j, SZ(s) / 2) {
            int l = i - j, r = i + 1 + j;
            if (l < 0 || r >= SZ(s)) break;
            if (s[l] == s[r]) {
                c += 2;
            }
        }
        // if (c > ans) out(c);
        chmax(ans, c);
    }
    rep(i, SZ(s)) {
        string t = s;
        int c = 1;
        rep3(j, 1, min(i, SZ(s) - (i + 1)) + 1) {
            if (s[i - j] == s[i + j]) c += 2;
        }
        // out(c);
        chmax(ans, c);
    }
    out(ans);
}