#include "bits/stdc++.h"
#define IOS ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define ll long long
#define ull unsigned long long
#define OPEN freopen (".in", "r", stdin); freopen (".out", "w", stdout);
#define pc __builtin_popcount
#define db double
#define pii pair<int, int>
#define fi first
#define se second
#define F(i,x,y) for (int i = (x); i <= (y); ++i)
#define D(i,x,y) for (int i = (x); i >= (y); --i)

using namespace std;

const ll inf = 1ll * 1e18;
//const ll mod = 998244353ll;

const ll mod = 1ll * 1e9 + 7ll;

inline void Rd(int& x) {
	int f = 1;
	x = 0;
	char c = getchar();
	while (c < '0' || c > '9') {
		if (c == '-') f = -1;
		c = getchar();
	}
	while (c >= '0' && c <= '9') x = (x << 3) + (x << 1) + (c - 48), c = getchar();
	x *= f;
}

inline void Wt(int x) {
	if (x < 10) {
		putchar(x + 48);
		return;
	}
	Wt(x / 10);
	putchar((x % 10) + 48);
}

bool st;

int d[33000020];

string s, t;
int n;
bool ed;

int ans;

int main() {
	cerr << (&st - &ed) / 1024.0 / 1024.0 << '\n';
	
	cin >> s; s = ' ' + s;
	
	F(i, 1, s.size() - 1) {
		t += '#';
		t += s[i];
	} 
	
	t += '#'; n = t.size() - 1;
	
	cerr << t << ' ' << n <<'\n';
	int mx = 1;
	d[0] = 1; d[1] = 2;
	int r = 0;
	F(i, 2, n - 1) {
		r = mx + d[mx] - 1;
//		if (i > r) continue ;
		
		int mn = min(r - i + 1, d[2 * mx - i]);
//		cerr << i << ':' << d[2 * mx - i] << ' ' << r - i + 1 << '\n';
//		cerr << r << ' ' << 2 * mx - i << ' ' << mn << ' ' << mx << '\n';
		int j, k;
		for (j = i - mn + 1, k = i + mn - 1; j >= 0 && k < n && t[j] == t[k]; -- j, ++ k) ;
//		cerr << j << ' ' << k << ' ' << t[j] << ' ' << t[k] << '\n';
		d[i] = i - j;
		if (i + d[i] - 1 > mx) mx = i;
		ans = max(ans, d[i]);
	}
//	F(i, 1, n) cerr << d[i] << ' '; cerr << '\n'; 
	cout << ans - 1;
}

#4 TLE，WA 了三个点（#8，#11，#15）。