#include <bits/stdc++.h>
using namespace std;
#define int long long int
 
signed main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    string s;
    cin >> s;
    int n = (int) s.size(), l = 1, r = n, ans = n;
    vector<int> vis(26, 0);
    int need = 0;
    for(auto x : s){
        if(!vis[x - 'a']){
            need += 1;
        }
        vis[x - 'a'] += 1;
    }
    auto possible = [&](int x){
         vis.assign(26, 0); int cnt = 0;
         for(int i = 0; i < x; i++){
             if(!vis[s[i] - 'a']){
                 cnt += 1;
             }
             vis[s[i] - 'a'] += 1;
         }
        if(cnt == need)return true;
        int pt = x;
        while (pt < n){
            if(!vis[s[pt] - 'a']){
                cnt += 1;
            }
            if(vis[s[pt - x] - 'a'] - 1 == 0){
                cnt -= 1;
            }
            vis[s[pt] - 'a'] += 1;
            vis[s[pt - x] - 'a'] -= 1;
            pt += 1;
            if(cnt == need)return true;
        }
        return false;
    };
    while (l <= r){
        int m = (l + r) >> 1;
        if(possible(m)){
            ans = m;
            r = m - 1;
        }else l = m + 1;
    }
    cout << ans << '\n';
    return 0;
}