#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 cr,l,i,j;
    int c[501];
    memset(c,0,sizeof(c));
    for (i=1;i<=A;i++) {
        cr=0;
        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];
        }
    }
    l=0;
    for (i=1;i<=max(A,B);i++)
        if (c[i]>l)
            l=c[i];
    return l;
}

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,2*LCIS(A,B)+1);
    }
    g << sol << '\n';
    f.close();g.close();
    return 0;
}