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

    def binary_search(l, r, i, j):
        if l > r: return -1
        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 = binary_search(0, r, i, i)
        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 e != -1: ans = max(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 e != -1: ans = max(ans, (d+e)*2)

    for i in range(n-1):
        r = min(i, n-i-1)
        if r*2+1 <= ans: continue
        d = binary_search(0, r, i, i+1)
        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 e != -1: ans = max(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 e != -1: ans = max(ans, (d+e)*2+1)

    print(ans)

solve()