string1

#include <bits/stdc++.h>
using namespace std;
#define      mxx                 LLONG_MAX
#define      mnn                 LLONG_MIN
#define      Y()                 cout<< "YES" <<endl
#define      N()                 cout << "NO"<<endl
#define      endl                "\n"
#define      max_3(a,b,c)        max(a, max(b,c))
#define      min_3(a,b,c)        min(a, min(b,c))
#define      gcd(a,b)            __gcd(a,b)
#define      lcm(a,b)           (a*b)/gcd(a,b)
#define      loser               return 0
#define      ll                  long long
#define      PI                  acos(-1)
#define      mem(a,v)            memset(a,v,sizeof(a))
#define      SORT(v)             sort(v.begin(),v.end())
#define      REV(v)              reverse(v.begin(),v.end())
#define      B                   begin()
#define      E                   end()
#define      V                   vector
#define      F                   first
#define      S                   second
#define      PSB                 push_back
#define      MP                  make_pair
#define      flash               cout.flush()
#define      InTheNameOfGod      ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);

/*------------------START---------------------*/
ll cnt[30];
string ss[30];
/*-----*/
void solve(){
   ll n,ans=0;
   string s,answer;
   cin>>s;
   ll len=s.length();
   for(ll i=0;i<len;i++){
    ll ch=s[i]-'a';
    ll mx=0;
    string aux;
    for(ll j=0;j<=ch;j++){
        if((cnt[j])>mx){
            aux=ss[j];
            mx=cnt[j];
        }
    }
    cnt[ch]=++mx;
    aux+=(ch+'a');
    ss[ch]=aux;
    if(cnt[ch]>ans){
        ans=cnt[ch];
        answer=ss[ch];
    }
    else if(cnt[ch]==ans)
        answer=min(answer,ss[ch]);
   }
   cout<<ans<<endl;
   cout<<answer<<endl;



}
/*-----*/
int main(){
   InTheNameOfGod

   ll Test=1;
   //cin>>Test;
   while(Test--){
     solve();
    }
  loser;

}
///////   C O D I N G  I S  L I F E   ///////