#include <bits/stdc++.h>
using namespace std;

int io_=[](){ ios::sync_with_stdio(false); cin.tie(nullptr); return 0; }();

using LL = long long;
using ULL = unsigned long long;
using LD = long double;
using PII = pair<int, int>;
using VI = vector<int>;
using MII = map<int, int>;

template<typename T> void cmin(T &x,const T &y) { if(y<x) x=y; }
template<typename T> void cmax(T &x,const T &y) { if(x<y) x=y; }
template<typename T> bool ckmin(T &x,const T &y) { 
    return y<x ? (x=y, true) : false; }
template<typename T> bool ckmax(T &x,const T &y) { 
    return x<y ? (x=y, true) : false; }
template<typename T> void cmin(T &x,T &y,const T &z) {// x<=y<=z 
    if(z<x) { y=x; x=z; } else if(z<y) y=z; }
template<typename T> void cmax(T &x,T &y,const T &z) {// x>=y>=z
    if(x<z) { y=x; x=z; } else if(y<z) y=z; }

// mt19937 rnd(chrono::system_clock::now().time_since_epoch().count());
// mt19937_64 rnd_64(chrono::system_clock::now().time_since_epoch().count());

/*
---------1---------2---------3---------4---------5---------6---------7---------
1234567890123456789012345678901234567890123456789012345678901234567890123456789
*/

void solve() {
  string s; cin >> s;
  int n = s.length();

  vector<int> lst(26, -1);
  vector<int> mx(26);

  for (int i = 0; i < n; i++) {
    int c = s[i] - 'a';
    cmax(mx[c], i - lst[c]);
    lst[c] = i;
  }
  int ans = n;
  for (int i = 0; i < 26; i++) {
    cmax(mx[i], n - lst[i]);
    cmin(ans, mx[i]);
  }
  cout << ans << '\n';
}

int main() {
  int t = 1; 
  // cin >> t;
  while (t--) {
    solve();
  }
  return 0;
}