#ifdef LOCAL111
	#define _GLIBCXX_DEBUG
#else
	#define NDEBUG
#endif
#include <bits/stdc++.h>
const int INF = 1e9;
using namespace std;
template<typename T, typename U> ostream& operator<< (ostream& os, const pair<T,U>& p) { cout << '(' << p.first << ' ' << p.second << ')'; return os; }

#define endl '\n'
#define ALL(a)  (a).begin(),(a).end()
#define SZ(a) int((a).size())
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define RFOR(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define REP(i,n)  FOR(i,0,n)
#define RREP(i,n) for (int i=(n)-1;i>=0;i--)
#ifdef LOCAL111
	#define DEBUG(x) cout<<#x<<": "<<(x)<<endl
	template<typename T> void dpite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;}
#else
	#define DEBUG(x) true
	template<typename T> void dpite(T a, T b){ return; }
#endif
#define F first
#define S second
#define SNP string::npos
#define WRC(hoge) cout << "Case #" << (hoge)+1 << ": "
template<typename T> void pite(T a, T b){ for(T ite = a; ite != b; ite++) cout << (ite == a ? "" : " ") << *ite; cout << endl;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}

typedef long long int LL;
typedef unsigned long long ULL;
typedef pair<int,int> P;
typedef pair<LL,LL> LP;

void ios_init(){
	//cout.setf(ios::fixed);
	//cout.precision(12);
#ifdef LOCAL111
	return;
#endif
	ios::sync_with_stdio(false); cin.tie(0);	
}

int main()
{
	ios_init();
	string s;
	while(cin >> s) {
		vector<int> dp(1<<SZ(s),-1);
		int n = SZ(s);
		DEBUG(s);
		function<int(int)> rec = [&](int mask) -> int{
			if(dp[mask] != -1) return dp[mask];
			int res = 0;
			REP(i,n) FOR(j,i+1,n) FOR(k,j+1,n){
				if(!((mask>>i)&1) and !((mask>>j)&1) and !((mask>>k)&1) and s[j] == s[k] and s[j] != s[i]){
					// DEBUG((s[i]-'0')*100+(s[j]-'0')*10+(s[k]-'0'));
					res = max(res,
						rec(mask|(1<<i)|(1<<j)|(1<<k))+(s[i]-'0')*100+(s[j]-'0')*10+(s[k]-'0'));
				}
			}
			DEBUG(bitset<10>(mask));
			DEBUG(res);
			return dp[mask] = res;
		};
		cout << rec(0) << endl;
	}
	return 0;
}