#include <fstream>
#include <cstring>
using namespace std;

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

string s;
int i,n,v[501],sol=0,j,a[501],A,b[501],B;

int LCIS (int A,int B,int x) {
    int cr,l,i,j,ap=0,s;
    int c[501];
    memset(c,0,sizeof(c));
    for (i=1;i<=A;i++) {
        cr=0;
        if (a[i]==x) ap++;
        for (j=1;j<=B;j++) {
            if (a[i]==b[j] && cr+1>c[j])
                c[j]=cr+1;
            if (b[j]<a[i] && cr<c[j])
                cr=c[j];
            if (b[j]==x && i==1) ap++;
        }
    }
    l=0;int ind=-1;
    for (i=1;i<=max(A,B);i++)
        if (c[i]>l) {
            l=c[i];
            ind=i;
        }
    //if (b[ind]!=x) s=2*l+1;
        /*else*/ s=2*l;
    if (ap%2==0) s-=1;
        else s-=0;
    return s;
}

int main () {
    f >> s;
    n=s.size();
    for (i=1;i<=n;i++) v[i]=int(s[i-1])-int('a')+1;
    for (i=2;i<n;i++) {
        A=B=0;memset(a,0,sizeof(a));memset(b,0,sizeof(b));
        for (j=1;j<=i;j++)
            if (v[j]<=v[i]) a[++A]=v[j];
        for (j=n;j>=i;j--)
            if (v[j]<=v[i]) b[++B]=v[j];
        sol=max(sol,LCIS(A,B,v[i]));
    }
    g << sol << '\n';
    f.close();g.close();
    return 0;
}