// luogu-judger-enable-o2

#include <cstdio>

#include <algorithm>

#include <cstring>

#define maxn 300005

#define setIO(s) freopen(s".in","r",stdin)

using namespace std;

char str[maxn];

int n,l[maxn],ans,r[maxn];

struct PAM{

    int fail[maxn],ch[maxn][30],len[maxn],tot,ss[maxn],last;

    void init(){

        ss[0] = -1,fail[0] = 1,last = 0,fail[1] = 0;

        len[0] = 0,len[1] = -1, tot = 1;

    }

    int newnode(int x){ len[++tot] = x; return tot;  }

    int getfail(int p,int nn){

        while(ss[nn - len[p] - 1] != ss[nn]) p = fail[p];

        return p;

    }

    void ins(int c,int i){

        int p = getfail(last,i);

        if(!ch[p][c]) {

            int q = newnode(len[p] + 2);

            fail[q] = ch[getfail(fail[p],i)][c];

            ch[p][c] = q;

        }

        last = ch[p][c];

    }

}A,B;

int main(){

    //setIO("input");

    scanf("%s",str+1),n = strlen(str + 1), A.init(),B.init();

    for(int i = 1;i <= n; ++i) A.ss[i] = str[i] - 'a';

    for(int i = n;i >= 1; --i) B.ss[n - i + 1] = str[i] - 'a';

    for(int i = 1;i <= n; ++i)

    {

        A.ins(A.ss[i],i);

        l[i] = A.len[A.last];

    }

    for(int i = 1;i <= n; ++i) B.ins(B.ss[i],i),r[n - i + 1] = B.len[B.last];

    for(int i = 1;i <= n - 1; ++i) ans = max(ans,l[i] + r[i + 1]);

    printf("%d",ans);

    return 0;

}