#include<bits/stdc++.h>
using namespace std;
 
string s;
int arr[200];
int unique_char = 0;
 
bool check(int mid) {
 
    memset(arr, 0, sizeof(arr));
    int i = 0;
    int j = 0;
    int cnt = 0;
 
    while(i<mid) {
        if(arr[s[i]]==0) {
            cnt++;
        }
        arr[s[i++]]++;
    }
    if(cnt>=unique_char)
        return true;
 
    while(i<s.size()) {
        if(arr[s[i]]==0)cnt++;
 
        arr[s[i++]]++;
 
        if(arr[s[j]]==1)cnt--;
 
        arr[s[j++]]--;
 
        if(cnt>=unique_char)return true;
    }
    if(cnt>=unique_char)return true;
 
    return false;
}
 
int solution() {
    for(int i=0; i<s.size(); i++) {
        if(arr[s[i]]==0) {
            arr[s[i]]=1;
            unique_char++;
        }
    }
 
    int lo = 1;
    int hi = s.size();
 
 
    while(hi-lo>1) {
        int mid = (lo+hi)/2;
 
        if(check(mid))hi = mid;
        else lo = mid;
 
    }
 
    while(check(hi-1))hi--;
 
    return hi;
}
 
 
int main() {
 
    cin>>s;
 
    int ans = solution();
 
    cout << ans << "\n";
 
 
 
 
    return 0;
}