def t(X):
    if X=="":
        return 0
    if len(X)==1:
        return 1

    K=-1
    I,J=0,len(X)-2

    while True:
        while True:
            if I>0 and X[I:J+1]==X[J:I-1:-1]:
                break

            if I==0 and X[:J+1]==X[J::-1]:
                break

            J-=1
        K=max(K,J-I+1)
        I=J+1
        J=len(X)-1

        if I==len(X):
            break
    return K

S=input()
K=t(S)

for i in range(len(S)):
    for j in range(i+1,len(S)):
        K=max(K,t(S[i:j]))
print(K)