Cod sursa(job #637142)
#include <cstdio>
#include <string.h>
#include <algorithm>
#include <stdlib.h>
using namespace std;
#define MAXN 512
char S[MAXN];
int i,j,N,L,Lmax;
int mem[MAXN][MAXN];
int caut(int a, int b) {
if(a>b) return 0;
if(a==b && S[a]>=S[a-1]) return 1;
if(mem[a][b]>=0) return mem[a][b];
int i,j,R=0; char Min='z'+1;
for(i=a;i<b;i++) {
for(j=b;j>i;j--)
if(S[i]==S[j] && S[i]>=S[a-1] && S[i]<Min) {
R=max(R,2+caut(i+1,j-1));
//if(S[i]==S[a-1]) break;
Min=min(Min,S[i]);
}
if(S[i]>=S[a-1])
R=max(R,1);
}
return mem[a][b]=R;
}
int main() {
freopen("palm.in","r",stdin);
freopen("palm.out","w",stdout);
//scanf("%s",&S);
fgets(S,sizeof(S),stdin);
N=strlen(S);
for(i=0;i<N;i++)
for(j=i;j<N;j++)
mem[i][j]=-1;
//memset(mem,-1,sizeof(mem));
Lmax=1;
for(i=0;i<N-1;i++)
for(j=N-1;j>i+Lmax-1;j--) {
if(S[i]!=S[j]) continue;
L=2+caut(i+1,j-1);
Lmax=max(Lmax,L);
}
printf("%d",Lmax);
}