Problem:
Score : 300 points

Problem Statement

Snuke can change a string t of length N into a string t' of length N - 1 under the following rule:

For each i (1 ≤ i ≤ N - 1), the i-th character of t' must be either the i-th or (i + 1)-th character of t.

There is a string s consisting of lowercase English letters.
Snuke's objective is to apply the above operation to s repeatedly so that all the characters in s are the same.
Find the minimum necessary number of operations.

Constraints

1 ≤ |s| ≤ 100

s consists of lowercase English letters.

Input

Input is given from Standard Input in the following format:

s

Output

Print the minimum necessary number of operations to achieve the objective.

Sample Input 1

serval

Sample Output 1

3

One solution is: serval → srvvl → svvv → vvv.

Sample Input 2

jackal

Sample Output 2

2

One solution is: jackal → aacaa → aaaa.

Sample Input 3

zzz

Sample Output 3

0

All the characters in s are the same from the beginning.

Sample Input 4

whbrjpjyhsrywlqjxdbrbaomnw

Sample Output 4

8

In 8 operations, he can change s to rrrrrrrrrrrrrrrrrr.

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#include <iomanip>

using namespace std;

typedef long long LL;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef long double LD;
typedef pair<LD, LD> PLDLD;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)
#define CLR(a) memset((a), 0 ,sizeof(a))
#define ALL(a) a.begin(),a.end()

const double eps=1e-5;
const int INF=1e9;


int main()
{
    string s;
    cin>>s;
    int ans=INF;
    REP(tt,26)
    {
        int cnt=0;
        string t=s;
        char c=tt+'a';
        bool flag=1;
        REP(i,t.size())
        {
            if(t[i]!=c)
            flag=0;
        }
        if(flag)
        {
            cout<<0<<endl;
            return 0;
        }
        flag=1;
        while(flag)
        {
            flag=0;
            REP(i,t.size()-1-cnt)
            {
                if(t[i]==c || t[i+1]==c)
                    t[i]=c;
                else
                {
                    flag=1;
                }
            }
            cnt++;
        }
        ans=min(ans,cnt);
    }
    cout<<ans<<endl;
}