#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9+7, N = 1e5 + 7;
 
string s;
int n, unq;
 
int dp[N][27];
 
void precal() {
  vector<int> v(26, 0);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < 26; j++) dp[i+1][j] = dp[i][j];
    dp[i+1][s[i] - 'a']++;
  }
}
 
bool bee(int m) {
  for (int i = 0; i + m <= n; i++) {
    int u = 0;
    for (int j = 0; j < 26; j++) {
      u += (dp[i+m][j] - dp[i][j]);
    }
    if(u >= unq) return true;
  } 
  return false;
}
 
int32_t main () {
  ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
  cin >> s;
  n = s.size();
  precal();
  unq = 0;
  vector<int> v(26, 0);
  for (int i = 0; i < n; i++) {
    if(v[s[i] - 'a'] == 0) unq++;
    v[s[i] - 'a']++;
  }
 
  int l = 1, r = n, mid, ans = inf;
  while(l <= r) {
    mid = (l+r) >> 1;
    if(bee(mid)) {
      ans = min(ans, mid);
      r = mid - 1;
    }
    else l = mid + 1;
 
  }
  cout << ans << endl;
}