#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define rrep(i,n) for (int i = (n)-1; i >=0; --i)
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

using namespace std;
using ll = long long;
using ld = long double;
using pi = pair<ll, ll>;

// auto mod int
// https://youtu.be/L8grWxBlIZ4?t=9858
// https://youtu.be/ERZuLAxZffQ?t=4807 : optimize
// https://youtu.be/8uowVvQ_-Mo?t=1329 : division
const int mod = 998244353;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x=0):x((x%mod+mod)%mod){}
  mint operator-() const { return mint(-x);}
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod-a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;}
  mint operator+(const mint a) const { return mint(*this) += a;}
  mint operator-(const mint a) const { return mint(*this) -= a;}
  mint operator*(const mint a) const { return mint(*this) *= a;}
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t>>1);
    a *= a;
    if (t&1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) const { return mint(*this) /= a;}
};
istream& operator>>(istream& is, const mint& a) { return is >> a.x;}
ostream& operator<<(ostream& os, const mint& a) { return os << a.x;}
// combination mod prime
// https://www.youtube.com/watch?v=8uowVvQ_-Mo&feature=youtu.be&t=1619
struct combination {
  vector<mint> fact, ifact;
  combination(int n):fact(n+1),ifact(n+1) {
    assert(n < mod);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i) fact[i] = fact[i-1]*i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i) ifact[i-1] = ifact[i]*i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n) return 0;
    return fact[n]*ifact[k]*ifact[n-k];
  }
} c(200005);

ll ans = 1e18;

void bfs(ll x, ll y, vector<string> &ban,vector<pi> &kiseki, ll gx, ll gy, ll cnt){
  if(x<0 || y<0 || cnt>300) return;
  if(x==gx && y==gy) {
    chmin(ans, cnt) ;
    return;
  }
  else{
    bool flug = true;
    rep(i, kiseki.size()){
      if(kiseki[i].first==x+1 && kiseki[i].second==y) {
	flug = false;
	break;
      }
    }
    if(flug){
      kiseki.push_back(make_pair(x+1, y));
      bfs(x+1, y, ban, kiseki, gx, gy, cnt+1);
      kiseki.pop_back();
    }
    flug = true;
    rep(i, kiseki.size()){
      if(kiseki[i].first==x-1 && kiseki[i].second==y) {
	flug = false;
	break;
      }
    }
    if(flug){
      kiseki.push_back(make_pair(x-1, y));
      bfs(x-1, y, ban, kiseki, gx, gy, cnt+1);
      kiseki.pop_back();
    }

    flug = true;
    rep(i, kiseki.size()){
      if(kiseki[i].first==x && kiseki[i].second==y+1) {
	flug = false;
	break;
      }
    }
    if(flug){
      kiseki.push_back(make_pair(x, y+1));
      bfs(x, y+1, ban, kiseki, gx, gy, cnt+1);
      kiseki.pop_back();
    }

    flug = true;
    rep(i, kiseki.size()){
      if(kiseki[i].first==x && kiseki[i].second==y-1) {
	flug = false;
	break;
      }
    }
    if(flug){
      kiseki.push_back(make_pair(x, y-1));
      bfs(x, y-1, ban, kiseki, gx, gy, cnt+1);
      kiseki.pop_back();
    }

  }
}

int main() {
  string tmp;
  cin >> tmp;
  ll n = tmp.size();

  
  ll ans = 1111;
  map<char, int> m;
  rep(i, tmp.size()){
    if(m[tmp[i]] || i==0) continue;
    m[tmp[i]]++;
    ll candidate = i;
    ll last = i;

    for(int j=i+1;j<n;j++){
      if(tmp[i]==tmp[j]) {
	candidate = max(candidate, j-last-1);
	last = j;
      }
      else if(j==tmp.size()-1) candidate = max(candidate, n-1-last);

    }
    ans = min(ans, candidate);
  }

  int cnt = 0;
  for(auto x:m){
    cnt++;
  }

  if(cnt==1) ans = 0;
  
  cout << ans << endl;
  return 0;
}


Measured memory_bytes: 6248