#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define pf push_front
#define pb push_back
#define mk make_pair
#define all(c) (c).begin(), (c).end()
#define sz(x) (int)x.size()
#define SWS ios_base::sync_with_stdio(false)
#define rfile freopen("input.txt", "r", stdin)
#define wfile freopen("output.txt", "w", stdout)
#define files rfile; wfile

typedef long long ll;
typedef long double ld;

const int Z = (int)1e5 + 111;
const int inf = (int)1e9 + 111;
const ll llinf = (ll)1e18 + 5;
const int MOD = (int)1e9 + 7;

vector<int> dd1 (string s) {
int   n = sz(s);
    vector<int> d1 (n);
int l=0, r=-1;
for (int i=0; i<n; ++i) {
	int k = (i>r ? 0 : min (d1[l+r-i], r-i)) + 1;
	while (i+k < n && i-k >= 0 && s[i+k] == s[i-k])  ++k;
	d1[i] = k--;
	if (i+k > r)
		l = i-k,  r = i+k;
}
return d1;
}

vector <int> dd2 (string s) {
  int  n = sz(s);
vector<int> d2 (n);
int l=0, r=-1;
for (int i=0; i<n; ++i) {
	int k = (i>r ? 0 : min (d2[l+r-i+1], r-i+1)) + 1;
	while (i+k-1 < n && i-k >= 0 && s[i+k-1] == s[i-k])  ++k;
	d2[i] = --k;
	if (i+k-1 > r)
		l = i-k,  r = i+k-1;
}
return d2;
}

int main () {
	srand(time(0));
	//files;
    string s, t;
    cin >> s;
    t = s;
    //reverse(all(t));
    s.pop_back();
    s = t + s;
	//cout << s << '\n';
    vector <int> ans;
    vector <int> d1 = dd1(s), d2 = dd2(s);

    for (int i = 0; i < d1.size(); i++) {
    	ans.pb(d1[i] * 2 - 1);
    	ans.pb(d2[i] * 2);
	}
	int aans = 0;
	for (int i = 0; i < ans.size(); i++)
		if (ans[i] <= t.length()) {
			aans = max(aans, ans[i]);
		}
	cout << aans;

	return 0;
}