#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <bitset>
#include <functional>
using namespace std;

#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define mp(a,b) make_pair((a),(b))
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<(x)<<endl
#define fi first
#define se second

#define INF 2147483600

int dfs(vector<int> &vec,int s){
  int ret = 0;
  repl(i,s,vec.size()) if(vec[i]!=-1){
    for(int j=i+1; j<vec.size(); j++) if(vec[i]!=vec[j] && vec[j]!=-1){
      for(int k=j+1; k<vec.size(); k++) if(vec[j]==vec[k]){
        int tmp1=vec[i], tmp2=vec[j];
        vec[i]=vec[j]=vec[k]=-1;
        int r=dfs(vec,i+1);
        ret = max(ret, tmp1*100 + tmp2*10 + tmp2 + r);
        vec[i]=tmp1;
        vec[j]=vec[k]=tmp2;
      }
    }
  }
  return ret;
}

int main(){
  string s;
  cin>>s;
  vector<int> vec(s.size());
  rep(i,s.size())vec[i] = s[i]-'0';

  cout<<dfs(vec,0)<<endl;
  return 0;
}