#include <cstring>

 #include <iostream>

 #include <cstdio>

 using namespace std;

 #define inf (1LL << 30) 

 const int N = ;

 char str[N];

 int tmp[N];

 int arr[N];

 bool vis[];

 int main(){

     ios::sync_with_stdio(false);

     cin.tie();

     cin >> str;

     int len = strlen(str) - ;

     for(int i = ; i <= len; i++){

         arr[i] = str[i] - 'a' + ;

         vis[arr[i]] = true;  //哪些字符出现过

     }

     int dis1 = inf;

     int dis2 = inf;

     int l = ;

     for(int o = ; o < ; o++){ //'a'~'z'

         if(!vis[o]) continue;

         l = ;

         for(int i = ; i <= len; i++){

             if(o == arr[i]) tmp[l++] = i;

         }

         --l;

         //出现一次的

         if(l == ){

             int v = ;

             v = max(v,max(tmp[l] -  + ,len - tmp[] + ));

             dis1 = min(dis1,v);

         }

         //出现多次的

         else{

             int v = ;

             for(int i = ; i <= l; i++){

                 v = max(v,tmp[i] - tmp[i - ]);

             }

             v = max(v,tmp[] -  + ); //与字符串开头

             v = max(v,len - tmp[l] + );//与字符串结尾

             dis2 = min(dis2,v);

         }

     }

     cout << min(dis1,dis2) << endl;

     getchar();getchar();

     return ;

 }