#include <bits/stdc++.h>
#define rep(i, f, t) for(int i(f); i <= t; ++i)
#define re(i, t) for(int i(1); i <= t; ++i)
#define per(i, t, f) for(int i(t); i >= f; --i)
#define pe(i, t) for(int i(t); i >= 1; --i) 
#define nx(i, u) for(int i(head[u]); i; i = e[i].nxt)
typedef long long ll;
typedef unsigned long long ull; 
using namespace std;
typedef pair <int, int> pii;
#define pb push_back 
#define fi first
#define i128 __int128
#define se second
#define Ls (ix(l, mid))
#define Rs (ix(mid+1, r))
#define ix(l, r) ((l + r) | (l != r))  
#define mp(i, j) (make_pair(i, j))
//#define int long long
#define inf 0x3f3f3f3f
#define INF 0x3f3f3f3f3f3f3f3f
 
struct IO {
    #define MAXSIZE 1<<21
    #define isdigit(x) (x >= '0' && x <= '9')
    #define isspace(x) (x == ' ' || x == '\n' || x == '\r' || x == '\t')
    char ibuf[MAXSIZE], obuf[MAXSIZE], *s1, *s2, *s3, endl, blank;
    int round[10] = {0, 0, 0, 0, 0, 1, 1, 1, 1}, sta[65], precisions;
    bool fail;
    FILE *in_stream, *out_stream;
    IO(FILE *_stream = stdin, FILE *__stream = stdout) { reset(_stream,__stream); }
    #if DEBUG
    #else
        ~IO() {close();}
    #endif
    inline void reset (FILE *_stream = stdin, FILE *__stream = stdout, bool reset = true) {
        s1 = s3 = ibuf, s2 = obuf, in_stream = _stream, out_stream = __stream, fail = false;
        if(reset) { endl = '\n'; blank = ' '; precisions = 6; }
    }
    inline void flush_in() {s3 = (s1 = ibuf) + fread(ibuf, 1, MAXSIZE, in_stream); }
    inline void flush_out() { fwrite(obuf, 1, s2-obuf, out_stream), s2 = obuf; }
    inline void flush_out_with_stream() { flush_out(); fflush(out_stream); } 
    inline char get() {
        #if DEBUG  
            return getchar();
        #endif
        return s1 == s3 && (flush_in(), fail = s1 == s3) ? 0 : *s1++;
    }
    inline void put(char ch) {
        #if DEBUG
            putchar(ch);
        #else
            s2-obuf == MAXSIZE ? flush_out(), 0 : 0, *s2++=ch;
        #endif
    }
    template <class T>
    inline void read(T &x) {
        bool sign = false; char c = get(); x = 0;
        while(!isdigit(c) && c) {sign=c=='-'; c = get(); }
        while(isdigit(c)) { x = (x<<1) + (x<<3) + (c^'0'); c = get(); }
        sign ? x = ~x+1 : 0;
    }
    inline void read(double &x) {
        bool sign = false; char c = get(); x = 0;
        while(!isdigit(c) && c) { sign=c=='-'; c = get(); }
        while(isdigit(c)) { x = x * 10 + (c^'0'); c = get(); }
        if(c=='.') { c = get(); double tmp = 1; while(isdigit(c)) { tmp /= 10, x += tmp * (c^'0'); c = get(); } }
        sign ? x = -x : 0;
    }
    inline void read(long double &x) {
        bool sign = false; register char c = get(); x = 0;
        while(!isdigit(c) && c) { sign=c=='-'; c = get(); }
        while(isdigit(c)) { x = x * 10 + (c^'0'); c = get(); }
        if(c == '.') { c = get(); register long double tmp = 1; while(isdigit(c)) { tmp /= 10, x += tmp * (c^'0'); c = get(); } }
        sign ? x = -x : 0;
    }
    inline void read(char *s) {
        char c = get();
        while(isspace(c)) c = get();
        while(!isspace(c) && c) { *s++=c; c = get(); }
        *s = '\0';
    }
    inline void read(char &c) {
        do
            c = get();
        while(isspace(c));
    }
    template <class T, class ...Args>
    inline void read(T &x, Args &...args) { read(x), read(args...); }
    template <class T>
    inline void write(T x) {
        int top = 0;
        if(x<0) { put('-'); sta[top++] = ~(x%10)+1, x /= 10; x = ~x+1; }
        else sta[top++] = x%10, x /= 10;
        while(x) sta[top++] = x%10 ,x /= 10;
        while(top) put(sta[--top]^'0');
    }
    inline void write(double y) {
        int top = 0;
        if(y<0) { put('-'); y=-y; }
        int x = y; y -=x;
        write(x);
        if(y) {
            do
                sta[top++] = y*10, y = y*10 - sta[top-1];
            while(top<precisions-1);
            sta[top++] = y*10 + round[(int)((y*10-((int)(y*10)))*10)];
        }
        put('.');
        for(int i(0); i<top; ++i) put(sta[i]^'0');
        for(int i(top); i<precisions; ++i) put('0');
    }
    inline void write(long double y) {
        register int top = 0;
        if(y<0) { put('-'); y=-y; }
        int x = y; y -= x;
        write(x);
        if(y) {
            do
                sta[top++] = y*10, y = y*10 - sta[top-1];
            while(top<precisions-1);
            sta[top++] = y*10 + round[(int)((y*10-((int)(y*10)))*10)];
        }
        put('.');
        for(register int i(0); i < top; ++i) put(sta[i]^'0');
        for(register int i(top); i < precisions; ++i) put('0');
    }
    inline void write(const char ch) { put(ch); }
    inline void write(char *s) { while(*s!='\0') put(*s++); }
    inline void write(const char *s) { while(*s!='\0') put(*s++); }
    inline void write(const std::string str) { write(str.c_str()); }
    inline IO &precision(const int x) { precisions=x; return *this; }
    template <class T,class ...Args>
    inline void write(T x,Args ...args) { write(x), blank?put(blank), 0:0, write(args...); }
    template <class ...Args>
    inline void writeln(Args ...args) { write(args...), endl?put(endl), 0:0; }
    template <class T>
    inline IO &operator>>(T &x) { read(x); return *this; }
    inline IO &operator>>(IO &x) { return *this; }
    template <class T>
    inline IO &operator<<(const T x) { write(x); return *this; }
    inline IO &operator<<(IO &x) { return *this; }
    inline operator bool() { return !fail; }
    template <class T>
    inline operator T() { T x; read(x); return x; }
    inline void open(FILE *_stream=stdin,FILE *__stream=stdout) { close(), reset(_stream, __stream, false); }
    inline void close() { flush_out_with_stream(); fclose(in_stream), fclose(out_stream); }
    #define read(x) io>>x
    #define out(x) io<<x
}io; 

const int N = 2e6 + 5;
char a[N], s[N];
int len, n, p[N], ans;

void solve () {
	int id = 0, r = 0;
	re(i, len) {
		if(i <= r) {
			p[i] = min(r-i+1, p[2 * id - i]);
		}
		while(s[i+p[i]+1] == s[i-p[i]-1]) ++p[i];
		if(i + p[i] - 1 > r) {
			id = i;
			r = i + p[i] - 1;
		}
	}
	rep(i, 2, len-1) ans = max(ans, p[i]);
}

int main () {
	scanf("%s", a);
	n = strlen(a);
	len = 0;
	s[0] = '(';
	s[++len] = '#';
	rep(i, 0, n-1) {
		s[++len] = a[i];
		s[++len] = '#';
	}
	s[++len] = ')';
	solve();
	io << ans;
	return 0;
}