#include <bits/stdc++.h>
using namespace std;
int main() {
  string str;
  cin >> str;
  long long i, maxi[26] = {0};
  map<long long, long long> mp;
  long long n = str.size();
  for (i = 0; i < n; i++) {
    long long a = mp[str[i]];
    mp[str[i]] = i + 1;
    char c = str[i];
    maxi[c - 'a'] = max(maxi[c - 'a'], i + 1 - a);
  }
  for (i = 0; i < 26; i++) {
    maxi[i] = max(maxi[i], n + 1 - mp['a' + i]);
  }
  sort(maxi, maxi + 26);
  cout << maxi[0];
  return 0;
}
