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
s=input()
l=len(s)
ans=10000000000
arr=[[0,-1] for i in range(26)]
#print(s)
for i in range(l):
    k=ord(s[i])-ord('a')
    arr[k][0]=max(i-arr[k][1],arr[k][0])
    arr[k][1]=i
#    print(k,arr[k],arr)
#print(arr)      
for i in range(26):
    arr[i][1]=-1    
#print(arr)
for i in range(l-1,-1,-1):
    k=ord(s[i])-ord('a')
    if arr[k][1]==-1:
        arr[k][0]=max(l-1-i,arr[k][0])
        arr[k][1]=i
#    print(arr,k)    
#print(arr)    
for i in range(26):
    if arr[i][1]!=-1:
        ans=min(ans,arr[i][0])
print(ans)        

