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 poss(size,s,c):
    i=0
    flag=False
    while i<len(s):
        step=0
        inner=False
        while step<size and step+size<len(s):
            if s[step]==c:
                inner=True
                break
            step+=1
        if inner==False:
            flag=False
            break
        i+=2
    return flag
s=input()
maxi=[0 for i in range(26)]
setter=[0 for i in range(26)]
hash={'a':0,'b':1,'c':2,'d':3,'e':4,'f':5,'g':6,'h':7,'i':8,'j':9,'k':10,'l':11,'m':12,'n':13,'o':14,'p':15,'q':16,'r':17,'s':18,'t':19,'u':20,'v':21,'w':22,'x':23,'y':24,'z':25}
for i in range(len(s)):
    if setter[hash[s[i]]]:
        maxi[hash[s[i]]]=max(maxi[hash[s[i]]],i-setter[hash[s[i]]])
    setter[hash[s[i]]]=i
ans=float('inf')
for i in range(26):
    if maxi[i]:
        lo=1
        hi=maxi[i]
        i=chr(i+97)
        while hi-lo>1:
            mid=(lo+hi)//2
            if poss(mid,s,i):
                hi=mid
            else:
                lo=mid+1
        if poss(lo,s,i):
            ans=min(ans,lo)
        else:
            ans=min(ans,hi)
    else:
        pass
if ans==float('inf'):
    ans=len(s)//2+1
print(ans)