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>
using namespace std;
using ll=long long;
using vi=vector<int>;
using vvi=vector<vi>;
using vl=vector<ll>;
using vvl=vector<vl>;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
const ll LINF=0x1fffffffffffffff;
const int INF=0x3fffffff;
const int MOD=1000000007;
#define VAR(type,...) type __VA_ARGS__;in(__VA_ARGS__)
#define VEC(type,name,size) vector<type> name(size);each(x, name)in(x)
#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define rrep(i,a,b) for(int i=(a-1);i>=(b);--i)
#define each(x,v) for(auto &x:(v))
#define all(x) (x).begin(),(x).end()
#define print(...) out(__VA_ARGS__);cout<<endl
void in(){} template<class T,class... U> void in(T &t,U &...u){cin>>t;in(u...);}
void out(){} template<class T,class... U> void out(T t,U ...u){cout<<t<<" ";out(u...);}
void solve();
int main(){cin.tie(0);ios::sync_with_stdio(0);solve();}

void solve() {
  VAR(string, s);
  int ans = INF;
  rep(i, 'a', 'z' + 1) {
    int cnt = 0;
    string t = s;
    char c = i;
    while (1) {
      bool ok = true;
      each(x, t) {
        if (x != c) {
          ok = false;
          break;
        }
      }
      if (ok) {
        break;
      }
      int l = t.length() - 1;
      string tmp = string(l, '_');
      rep(i, 0, l) {
        if (t[i] == c || t[i + 1] == c) {
          tmp[i] = c;
        } else {
          tmp[i] = '_';
        }
      }
      t = tmp;
      cnt++;
    }
    ans = min(ans, cnt);
  }
  print(ans);
}