B

#букв английского алфавита, десятичных цифр и пробелов
alph = 'abcdefghijklmnopqrstuvwxyz' + ' ' + '0123456789'
met = {}
for l in alph:
    met[l] = -1

s = input()
n = len(s)
l = 0
r = 0
met[s[0]] = 0
maxl = 1
r += 1
while r < n:
    while met[s[r]] >= l and l + 1 < n:
        l += 1
        met[s[l]] = l
    cur = r - l + 1
    maxl = max(maxl, cur)
    met[s[r]] = r
    r += 1
print(maxl)
#pwwkEw