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 check(s, K):
	for ch in range(0, 26): 
		c = chr(97 + ch) 
		last = -1
		found = True
		for i in range(0, K): 
			if s[i] == c: 
				last = i 
		if last == -1: 
			continue
		for i in range(K, len(s)): 
			if s[i] == c: 
				last = i 
			if last <= (i - K): 
				found = False
				break

		if found: 
			return 1
	
	return 0

def binarySearch(s): 

	low, high, ans = 1, len(s), None
	
	while low <= high: 
		mid = (high + low) >> 1
		if check(s, mid): 
			ans, high = mid, mid - 1
		else: 
			low = mid + 1
	
	return ans 

s = input()
print(binarySearch(s)) 

