#include <fstream>
using namespace std;

const int N=501,C=26;
short int v[N][N][C],n;
char a[N],b[N];

ifstream in("palm.in");
ofstream out("palm.out");

void inv(char b[],char a[])
{
    for (int j=n,i=1;i<=n;i++,j--)
        b[j]=a[i];
}

void copy(short int v[],short int a[],short int b[])
{
    for (int i=0;i<C;i++)
        v[i]=a[i]>b[i] ? a[i] : b[i];
}

void copy(short int v[],short int a[],short int b[],short int g[],int p)
{
    for (int i=0;i<C;i++)
        v[i]=a[i]>b[i] ? a[i] : b[i];
    for (int i=p;i<C;i++)
        v[i]=g[p]+1>v[i] ? g[p]+1 : v[i];
}

int cmlscc()
{
    int rez=0,i,j;
    for (i=1;i<=n;i++)
    {
        for (j=1;j<=n-i+1;j++)
            if (a[i]!=b[j])
                copy(v[i][j],v[i-1][j],v[i][j-1]);
            else
                copy(v[i][j],v[i-1][j],v[i][j-1],v[i-1][j-1],a[i]-'a');
        if (2*v[i][n-i][C-1]>rez)
            rez=2*v[i][n-i][C-1];
        if (2*v[i][n-i+1][C-1]>rez)
            rez=2*v[i][n-i+1][C-1]-1;
    }
    return rez;
}

int main()
{
    in>>(a+1);
    for (n=1;a[n];n++);
    n--;
    inv(b,a);
    out<<cmlscc()<<"\n";
    return 0;
}