from string import ascii_lowercase X=ascii_lowercase+"0123456789" D={x:[] for x in X} S=input() N=len(S) for i in range(N): D[S[i]].append(i) #長さが奇数 K=0 for i in range(N): e=1 A=1 while 0<=i-e and i+e<N: if S[i-e]==S[i+e]:A+=2 e+=1 K=max(K,A) #長さが偶数 for x in D: E=D[x] L=len(E) for i in range(L): p=E[i] for j in range(i+1,L): e=1 A=2 q=E[j] while 0<=p-e and q+e<N: if S[p-e]==S[q+e]:A+=2 e+=1 K=max(K,A) print(K)