#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC push_options
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#include<bits/stdc++.h>
#include <xmmintrin.h>
#include <immintrin.h>
using namespace::std;
__attribute__((constructor))void init(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(15);}
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/priority_queue.hpp>
#include<ext/pb_ds/tag_and_trait.hpp>
// #include <boost/multiprecision/cpp_dec_float.hpp>
// #include <boost/multiprecision/cpp_int.hpp>
// namespace mp = boost::multiprecision;
// typedef mp::number<mp::cpp_dec_float<0>> cdouble;
// typedef mp::cpp_int cint;
template<typename T>using pbds=__gnu_pbds::tree<T,__gnu_pbds::null_type,less<T>,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<typename T>using pbds_map=__gnu_pbds::tree<T,T,less<T>,__gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<typename T,typename E>using hash_map=__gnu_pbds::gp_hash_table<T,E>;
template<typename T>using pqueue =__gnu_pbds::priority_queue<T, greater<T>,__gnu_pbds::rc_binomial_heap_tag>;
typedef long long lint;
#define INF (1LL<<60)
#define IINF (1<<30)
#define LINF (9223372036854775807LL)
#define EPS (1e-10)
#define endl ('\n')
//#define MOD 1000000007LL
#define MOD 998244353LL
//#define MOD 18446744069414584321ULL
typedef vector<lint> vec;
typedef vector<vector<lint>> mat;
typedef vector<vector<vector<lint>>> mat3;
typedef vector<string> svec;
typedef vector<vector<string>> smat;
template<typename T>inline void numout(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i<INF/2?i:"INF";f=1;}cout<<endl;}
template<typename T>inline void numout2(T t){for(auto i:t)numout(i);}
template<typename T>inline void output(T t){bool f=0;for(auto i:t){cout<<(f?" ":"")<<i;f=1;}cout<<endl;}
template<typename T>inline void output2(T t){for(auto i:t)output(i);}
template<typename T>inline void _output(T t){bool f=0;for(lint i=0;i<t.size();i++){cout<<f?"":" "<<t[i];f=1;}cout<<endl;}
template<typename T>inline void _output2(T t){for(lint i=0;i<t.size();i++)output(t[i]);}
#define rep(i,n) for(lint i=0;i<lint(n);++i)
#define repi(i,a,b) for(lint i=lint(a);i<(lint)(b);++i)
#define rrep(i,n) for(lint i=lint(n)-1;i>=0;--i)
#define rrepi(i,a,b) for(lint i=lint(b)-1;i>=lint(a);--i)
#define irep(i) for(lint i=0;;++i)
#define all(n) begin(n),end(n)
#define dist(a,b,c,d) sqrt(pow(a-c,2)+pow(b-d,2))
inline lint gcd(lint A,lint B){return B?gcd(B,A%B):A;}
inline lint lcm(lint A,lint B){return A/gcd(A,B)*B;}
// inline cint cgcd(cint A,cint B){return B?cgcd(B,A%B):A;}
// inline cint clcm(cint A,cint B){return A/cgcd(A,B)*B;}
bool chmin(auto& s,const auto& t){bool res=s>t;s=min(s,t);return res;}
bool chmax(auto& s,const auto& t){bool res=s<t;s=max(s,t);return res;}
const vector<lint> dx={1,0,-1,0,1,1,-1,-1};
const vector<lint> dy={0,1,0,-1,1,-1,1,-1};
#define SUM(v) accumulate(all(v),0LL)
auto call=[](auto f,auto... args){return f(f,args...);};
template<typename T,typename ...Args>auto make_vector(T x,int arg,Args ...args){if constexpr(sizeof...(args)==0)return vector<T>(arg,x);else return vector(arg,make_vector<T>(x,args...));}

template<typename T,typename F>
struct FPS_BASE:vector<T>{
    using vector<T>::vector;
    using P=FPS_BASE<T,F>;
    F fft;
    FPS_BASE(){}
    inline P operator +(T x)noexcept{return P(*this)+=x;}
    inline P operator -(T x)noexcept{return P(*this)-=x;}
    inline P operator *(T x)noexcept{return P(*this)*=x;}
    inline P operator /(T x)noexcept{return P(*this)/=x;}
    inline P operator <<(int x)noexcept{return P(*this)<<=x;}
    inline P operator >>(int x)noexcept{return P(*this)>>=x;}
    inline P operator +(const P& x)noexcept{return P(*this)+=x;}
    inline P operator -(const P& x)noexcept{return P(*this)-=x;}
    inline P operator -()noexcept{return P(1,T(0))-=P(*this);}
    inline P operator *(const P& x)noexcept{return this->operator*=(x);}
    inline P operator /(const P& x)noexcept{return P(*this)/=x;}
    inline P operator %(const P& x)noexcept{return P(*this)%=x;}
    P &operator +=(T x){
        if(this->size()==0)this->resize(1,T(0));
        (*this)[0]+=x;
        return (*this);
    }
    P &operator -=(T x){
        if(this->size()==0)this->resize(1,T(0));
        (*this)[0]-=x;
        return (*this);
    }
    P &operator *=(T x){
        for(int i=0;i<(int)this->size();++i){
            (*this)[i]*=x;
        }
        return (*this);
    }
    P &operator /=(T x){
        return (*this)*=(T(1)/x);
    }
    P &operator <<=(int x){
        P ret(x,T(0));
        ret.insert(ret.end(),begin(*this),end(*this));
        return (*this)=ret;
    }
    P &operator >>=(int x){
        P ret;
        ret.insert(ret.end(),begin(*this)+x,end(*this));
        return (*this)=ret;
    }
    P &operator +=(const P& x){
        if(this->size()<x.size())this->resize(x.size(),T(0));
        for(int i=0;i<(int)x.size();++i){
            (*this)[i]+=x[i];
        }
        return (*this);
    }
    P &operator -=(const P& x){
        if(this->size()<x.size())this->resize(x.size(),T(0));
        for(int i=0;i<(int)x.size();++i){
            (*this)[i]-=x[i];
        }
        return (*this);
    }
    P &operator *=(const P& x){
        return (*this)=F()(*this,x);
    }
    P &operator /=(P x){
        if(this->size()<x.size()) {
            this->clear();
            return (*this);
        }
        const int n=this->size()-x.size()+1;
        return (*this) = (rev().pre(n)*x.rev().inv(n)).pre(n).rev(n);
    }
    P &operator %=(const P& x){
        return ((*this)-=*this/x*x);
    }
    inline P& shrink(){while((*this).back()==0)(*this).pop_back();return (*this);}
    inline P pre(int sz)const{
        return P(begin(*this),begin(*this)+min((int)this->size(),sz));
    }
    P rev(int deg=-1){
        P ret(*this);
        if(deg!=-1)ret.resize(deg,T(0));
        reverse(begin(ret),end(ret));
        return ret;
    }
    P inv(int deg=-1){
        assert((*this)[0]!=T(0));
        const int n=deg==-1?this->size():deg;
        P ret({T(1)/(*this)[0]});
        for(int i=1;i<n;i<<=1){
            ret=(ret*T(2)-ret*ret*pre(i<<1)).pre(i<<1);
        }
        return ret.pre(n);
    }
    inline P dot(const P& x){
        P ret(*this);
        for(int i=0;i<int(min(this->size(),x.size()));++i){
            ret[i]*=x[i];
        }
        return ret;
    }
    P diff(){
        P ret(*this);
        for(int i=0;i<(int)ret.size();i++){
            ret[i]*=i;
        }
        return ret>>1;
    }
    P integral(){
        P ret(*this);
        for(int i=0;i<(int)ret.size();i++){
            ret[i]/=i+1;
        }
        return ret<<1;
    }
    P log(int deg=-1){
        assert((*this)[0]==T(1));
        const int n=deg==-1?this->size():deg;
        return (diff()*inv(n)).pre(n-1).integral();
    }
    P exp(int deg=-1){
        assert((*this)[0]==T(0));
        const int n=deg==-1?this->size():deg;
        P ret({T(1)});
        for(int i=1;i<n;i<<=1){
            ret=ret*(pre(i<<1)+1-ret.log(i<<1)).pre(i<<1);
        }
        return ret.pre(n);
    }
	P pow(int c,int deg=-1){
		const int n=deg==-1?this->size():deg;
		long long i=0;
		P ret(*this);
		while(i!=(int)this->size()&&ret[i]==0)i++;
		if(i==(int)this->size())return P(n,0);
		if(i*c>=n)return P(n,0);
		T k=ret[i];
		return ((((ret>>i)/k).log()*c).exp()*(k.pow(c))<<(i*c)).pre(n);
	}
    P sqrt(int deg=-1){
        const int n=deg==-1?this->size():deg;
        if((*this)[0]==T(0)) {
            for(int i=1;i<(int)this->size();i++) {
                if((*this)[i]!=T(0)) {
                    if(i&1)return{};
                    if(n-i/2<=0)break;
                    auto ret=(*this>>i).sqrt(n-i/2)<<(i/2);
                    if((int)ret.size()<n)ret.resize(n,T(0));
                    return ret;
                }
            }
            return P(n,0);
        }
        P ret({T(1)});
        for(int i=1;i<n;i<<=1){
            ret=(ret+pre(i<<1)*ret.inv(i<<1)).pre(i<<1)/T(2);
        }
        return ret.pre(n);
    }
	P shift(int c){
		const int n=this->size();
		P f(*this),g(n,0);
		for(int i=0;i<n;++i)f[i]*=T(i).fact();
		for(int i=0;i<n;++i)g[i]=T(c).pow(i)/T(i).fact();
		g=g.rev();
		f*=g;
		f>>=n-1;
		for(int i=0;i<n;++i)f[i]/=T(i).fact();
		return f;
	}
    T eval(T x){
        T res=0;
        for(int i=(int)this->size()-1;i>=0;--i){
            res*=x;
            res+=(*this)[i];
        }
        return res;
    }
    vector<T> multipoint_eval(const vector<T>&x){
        const int n=x.size();
        P* v=new P[2*n-1];
        for(int i=0;i<n;i++)v[i+n-1]={T()-x[i],T(1)};
        for(int i=n-2;i>=0;i--){v[i]=v[i*2+1]*v[i*2+2];}
        v[0]=P(*this)%v[0];v[0].shrink();
        for(int i=1;i<n*2-1;i++){
            v[i]=v[(i-1)/2]%v[i];
            v[i].shrink();
        }
        vector<T>res(n);
        for(int i=0;i<n;i++)res[i]=v[i+n-1][0];
        return res;
    }
};

template<typename Mint>
struct _FPS9{
    auto operator()(auto s,auto t)->decltype(s){
        auto ntt=[](auto v,const int& h,const bool& inv){
            const int n=v.size();
            assert(Mint::get_mod()>=3&&Mint::get_mod()%2==1);
            decltype(v) tmp(n,Mint());
            Mint root=inv?Mint(Mint::root()).inv():Mint::root();
            for(int b=n>>1;b>=1;b>>=1,v.swap(tmp)){
                Mint w=root.pow((Mint::get_mod()-1)/(n/b)),p=1;
                for(int i=0;i<n;i+=b*2,p*=w)for(int j=0;j<b;++j){
                    v[i+j+b]*=p;
                    tmp[i/2+j]=v[i+j]+v[i+b+j];
                    tmp[n/2+i/2+j]=v[i+j]-v[i+b+j];
                }
            }
            if(inv)v/=n;
            return v;
        };
        const int n=s.size()+t.size()-1;
        int h=1;
        while((1<<h)<n)h++;
        s.resize((1<<h),Mint(0));
        t.resize((1<<h),Mint(0));
        return ntt(ntt(s,h,0).dot(ntt(t,h,0)),h,1).pre(n);
    }
};
template<typename Mint>using fps=FPS_BASE<Mint,_FPS9<Mint>>;

class mint {
  using u64 = std::uint_fast64_t;
    public:
    u64 a;
    constexpr mint(const long long x = 0)noexcept:a(x>=0?x%get_mod():get_mod()-(-x)%get_mod()){}
    constexpr u64 &value()noexcept{return a;}
    constexpr const u64 &value() const noexcept {return a;}
    constexpr mint operator+(const mint rhs)const noexcept{return mint(*this) += rhs;}
    constexpr mint operator-(const mint rhs)const noexcept{return mint(*this)-=rhs;}
    constexpr mint operator*(const mint rhs) const noexcept {return mint(*this) *= rhs;}
    constexpr mint operator/(const mint rhs) const noexcept {return mint(*this) /= rhs;}
    constexpr mint &operator+=(const mint rhs) noexcept {
        a += rhs.a;
        if (a >= get_mod())a -= get_mod();
        return *this;
    }
    constexpr mint &operator-=(const mint rhs) noexcept {
        if (a<rhs.a)a += get_mod();
        a -= rhs.a;
        return *this;
    }
    constexpr mint &operator*=(const mint rhs) noexcept {
        a = a * rhs.a % get_mod();
        return *this;
    }
    constexpr mint operator++(int n) noexcept {
        a += 1;
        if (a >= get_mod())a -= get_mod();
        return *this;
    }
    constexpr mint operator--(int n) noexcept {
        if (a<1)a += get_mod();
        a -= 1;
        return *this;
    }
    constexpr mint &operator/=(mint rhs) noexcept {
        u64 exp=get_mod()-2;
        while (exp) {
            if (exp % 2) {
                *this *= rhs;
            }
            rhs *= rhs;
            exp /= 2;
        }
        return *this;
    }
    constexpr bool operator==(mint x) noexcept {
        return a==x.a;
    }
    constexpr bool operator!=(mint x) noexcept {
        return a!=x.a;
    }
	constexpr bool operator<(mint x) noexcept {
        return a<x.a;
    }
	constexpr bool operator>(mint x) noexcept {
        return a>x.a;
    }
	constexpr bool operator<=(mint x) noexcept {
        return a<=x.a;
    }
	constexpr bool operator>=(mint x) noexcept {
        return a>=x.a;
    }
    constexpr static int root(){
        mint root = 2;
        while(root.pow((get_mod()-1)>>1).a==1)root++;
        return root.a;
    }
    constexpr mint pow(long long n){
        long long x=a;
        mint ret = 1;
        while(n>0) {
            if(n&1)(ret*=x);
            (x*=x)%=get_mod();
            n>>=1;
        }
        return ret;
    }
    constexpr mint inv(){
        return pow(get_mod()-2);
    }
    static vector<mint> fac,ifac;
    static bool init;
    constexpr static int mx=10000001;
    void build(){
        init=0;
        fac.resize(mx);
        ifac.resize(mx);
        fac[0]=1,ifac[0]=1;
        for(int i=1;i<mx;i++)fac[i]=fac[i-1]*i;
        ifac[mx-1]=fac[mx-1].inv();
        for(int i=mx-2;i>=0;i--)ifac[i]=ifac[i+1]*(i+1);
    }
    mint comb(lint b){
        if(init)build();
        if(a==0&&b==0)return 1;
        if((lint)a<b||a<0)return 0;
        return fac[a]*ifac[a-b]*ifac[b];
    }
    mint fact(){
        if(init)build();
        return fac[a];
    }
    mint fact_inv(){
        if(init)build();
        return ifac[a];
    }
    friend ostream& operator<<(ostream& lhs, const mint& rhs) noexcept {
        lhs << rhs.a;
        return lhs;
    }
    friend istream& operator>>(istream& lhs,mint& rhs) noexcept {
        lhs >> rhs.a;
        return lhs;
    }
    constexpr static u64 get_mod(){return MOD;}
};
vector<mint> mint::fac;
vector<mint> mint::ifac;
bool mint::init=1;

int main(){
    string s;
    cin>>s;
    lint ans=INF;
    rep(i,26){
        lint n=s.size();
        string u=s;
        lint cnt=0;
        while(1){
            if(count(all(u),i+'a')==u.size())break;
            string tmp;
            rep(j,u.size()-1){
                if(u[j]==char(i+'a')||u[j+1]==char(i+'a')){
                    tmp+=char(i+'a');
                }
                else tmp+=u[j];
            }
            u=tmp;
            cnt++;
        }
        chmin(ans,cnt);
    }
    cout<<ans<<endl;
}

Measured memory_bytes: 3620