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
#n=int(input())
l=[ord(i)-97 for i in input()]
maxi={}
n=len(l)
seen={}
for i in range(26):
    seen[i]=-1
for i in range(26):
    maxi[i]=-2347238
#print(seen[2])
for i in range(n):
    maxi[l[i]]=max(maxi[l[i]],i-seen[l[i]])
    seen[l[i]]=i 
for i in range(n):
    maxi[l[i]]=max(maxi[l[i]],n-seen[l[i]])
minim=10000000000000 
#print(maxi)
for i in range(26):
    if i not in l:
        continue
    if maxi[i]<minim:
        minim=maxi[i]
        ans=i 
print(minim)
        