s = list(input())
l = len(s)
ret = 0

for ti in range(l):
    for tj in range(ti,l):
        i = ti; j = tj
        tmp = 0
        while (i <= j):
            if s[i] == s[j]:
                if i == j:
                    tmp += 1
                else:
                    tmp += 2
            i += 1; j -= 1
        ret = max(ret,tmp)
print(ret)