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<cstdio>
#include<iostream>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;

char s1[1000];
int w[150],t[150],tt[150];
int ans,maxn,maxx,tot,ans2,ans22,anss,maxxx,maxnn,tott,minnn;
int main()
{
	int minn=0x7fffffff,minnn=0x7fffffff;
	scanf("%s",s1);
	int  n=strlen(s1);
	for(int i=0;i<n;i++)
	{
		w[s1[i]]++;
		if(w[s1[i]]>=2)t[++tot]=i;//maxn=w[s1[i]],
	}
	for(int j=1;j<=tot;j++)
	{
		ans=0,maxx=0;
		//whbrjpjyhsrywlqjxdbrbaomnw
		for(int i=0;i<n;i++)
		{
			if(s1[i]!=s1[t[j]])ans++;
			if(ans>maxx)maxx=ans;
			if(s1[i]==s1[t[j]])ans=0;
		}
		if(maxx<minn)minn=maxx;
	}
	ans2=(n+1)>>1;
	ans=min(ans2,minn);
	
	memset(w,0,sizeof(w));
		for(int i=0;i<n;i++)
	{
		w[s1[i]]++;
		if(w[s1[i]]>=maxnn)maxnn=w[s1[i]],tt[++tott]=i;
	}
	for(int j=1;j<=tott;j++)
	{
		anss=0,maxxx=0;
		//whbrjpjyhsrywlqjxdbrbaomnw
		for(int i=0;i<n;i++)
		{
			if(s1[i]!=s1[tt[j]])anss++;
			if(anss>maxxx)maxxx=anss;
			if(s1[i]==s1[tt[j]])anss=0;
		}
		if(maxxx<minnn)minnn=maxxx;
	}
	
	ans=min(ans,minnn);
	
	printf("%d\n",ans);
}