You are given a string *s* consisting of lowercase Latin letters. Character *c* is called *k*-dominant iff each substring of *s* with length at least *k* contains this character *c*.

You have to find minimum *k* such that there exists at least one *k*-dominant character.
The first line contains string *s* consisting of lowercase Latin letters (1 ≤ |*s*| ≤ 100000).
none
abacaba
2
zzzzz
1
abcde
3
bcaccacaaabaacaabaaabcbbcbcaacacbcbaaaacccacbbcbaabcbacaacbabacacacaccbbccbcbacbbbbccccabcabaaab
8
daabcdabbabbacacbaacabacbcaabaacac
4
abghim
4
gfliflgfhhdkceacdljgkegmdlhcgkcmlelmbbbmdddgdeeljjhgbbffmemmmkhebgkhadkdajabcjkcgbkgbaeacdedlkklfech
17
a
1
aaabbb
4
ab
2
abbb
2
ob
2
abccba
3
saaaaaaaas
2
axxx
2
abcba
2
abb
2
abcdea
4
axcbb
3
tmivvdcbbfrfogjviirrximhttoskopwrcmkcborcxvr
13
dlchmmuateksgldkckljrovmeuniobjrelqjpnjljlvhpqrjsfklliqpufplgaelevmlcnodbllquubobecem
15
zx
2
zxz
2
bbhdgaefbhf
6
xx
1
zxx
2
cbcada
4
z
1
aab
2
jficc
3
cceeaabfba
5
jk
2
lzeznbwu
5
rr
1
def possible(s,k):
	candidates = set(s[:k])
	count = {}
	for c in s[:k]:
		if c not in count:
			count[c] = 0
		count[c] += 1

	for i in range(k,len(s)):
		count[s[i-k]] -= 1
		if s[i] not in count:
			count[s[i]] = 0
		count[s[i]] += 1
		if count[s[i-k]]==0 and s[i-k] in candidates:
			candidates.remove(s[i-k])
	return len(candidates) > 0

def bs(s): #find the smallest k s.t. there is a k-dominant character
	L = 1
	R = len(s)
	while R-L > 1:
		M = (L+R)//2
		if possible(s,M):
			R = M
		else:
			L = M
	for ans in range(L,R+1):
		if possible(s,ans):
			return ans
	return -1

print(bs(input()))