def Manacher(s):
    dummy = "@"
    s = dummy+dummy.join(s)+dummy
    i = j = 0
    res = [-1]*len(s)
    while i < len(s):
        while i-j >= 0 and i+j < len(s) and s[i-j] == s[i+j]: j += 1
        res[i] = j-1
        k = 1
        while i-k >= 0 and k+res[i-k]+1 < j:
            res[i+k] = res[i-k]
            k += 1
        i += k
        j -= k
    return res

def solve():
    import sys

    def SI(): return sys.stdin.readline().rstrip()

    from random import randrange

    s = SI()
    n = len(s)
    BASE = randrange(128, 256)
    MOD = (1 << 61)-1

    h = [0]
    pw = [1]
    for c in s:
        h += [h[-1]*BASE%MOD+ord(c)]
        pw += [pw[-1]*BASE%MOD]

    rh = [0]
    for c in s[::-1]:
        rh += [rh[-1]*BASE%MOD+ord(c)]

    def hash(h, l, r):
        return (h[r]-h[l]*pw[r-l]%MOD)%MOD

    dia = Manacher(s)

    def binary_search(l, r, i, j):
        if l > r: return 0
        if l < 0: l = 0
        r += 1
        while l+1 < r:
            m = (l+r)//2
            if hash(h, i-m, i) == hash(rh, n-(j+m), n-j): l = m
            else: r = m
        return l

    ans = 1
    for i in range(1, n):
        r = min(i, n-i)
        if r*2 <= ans: continue
        d = dia[i*2]//2
        if d*2 == n:
            print(n-1)
            exit()
        # delete left
        ni, nj = i-d-1, i+d
        r = min(ni, n-nj)
        if ni >= 0 and (d+r)*2 > ans:
            e = binary_search(ans//2-d, r, ni, nj)
            if (d+e)*2 > ans: ans = (d+e)*2
        # delete right
        ni, nj = i-d, i+d+1
        r = min(ni, n-nj)
        if nj <= n and (d+r)*2 > ans:
            e = binary_search(ans//2-d, r, ni, nj)
            if (d+e)*2 > ans: ans = (d+e)*2

    for i in range(n-1):
        r = min(i, n-i-1)
        if r*2+1 <= ans: continue
        d = dia[i*2+1]//2
        if d*2+1 == n:
            print(n-1)
            exit()
        # delete left
        ni, nj = i-d-1, i+1+d
        r = min(ni, n-nj)
        if ni >= 0 and (d+r)*2+1 > ans:
            e = binary_search((ans-1)//2-d, r, ni, nj)
            if (d+e)*2+1 > ans: ans = (d+e)*2+1
        # delete right
        ni, nj = i-d, i+d+2
        r = min(ni, n-nj)
        if nj <= n and (d+r)*2+1 > ans:
            e = binary_search((ans-1)//2-d, r, ni, nj)
            if (d+e)*2+1 > ans: ans = (d+e)*2+1

    print(ans)

solve()